RyanMacRocks

Gotcha, I figured 500 watts was cutting it a bit close but didn't want to spend an extra $30 to step up to an 80 plus bronze and higher wattage. I may do so now to be safer. Thanks!

For sure, I'm buying it for the motherboards but this is just a bonus.

Seperate per business. And Universities and other institutions sell them off quite cheap, I've seen i7 950 systems for $50 on a deal site (someone snapped it up)

For a PC under $200, I don't think the buyer would be expecting a 1TB drive so I would go with the cheapest drive you can find. You can even look for bulk hard drives on sites like CDW or even eBay where you can get a pallet of old SATA II drives for cheap.

An online presence might be best for you. I don't know where you live but I can't think of many people who buy their PCs or hardware at brick and mortar stores these days. Here are the first steps I would take if I were you:
 
Research where you can get a steady stream of hardware to resell. Go register and LLC in your state. I don't know how much it costs in CA but I paid less than $150 for my LLC and the renewal is about $120 a year in Florida. Go setup a UPS and FedEx shipping account for your business. I believe setting up the account is free and the savings adds up when shipping computers (we ship large servers). Setup a website where you can sell your products (this is fairly easy to do). Setup business accounts with payment processors to handle payments (I recommend PayPal, Stripe, and BitPay). Once you have your online business setup, you're ready to go. For local customers you can process the sales locally (don't forget sales tax) and input them into your online billing system manually so at the end of the year you have one place to pull your finances from when it's time to deal with taxes.
 

the trick is to see if you got family that would loan you a few thousand to get started. hell I can go to my local e recycler and pick up sandy and ivy bridge i5s with 4-8gb of ram for 50-60$.
hey where in calli are you?

Also worth noting, sometimes the computers are leased and in inventory and they're on "the books" as yearly costs.
So they have to give the to some company that can give them a certificate or something that would make it possible to remove the monthly expense from budgets
Or, company like Dell makes a deal like 10-15% off if you return hardware  (and they put it in containers and ship to India or other countries, lightly refurbished and resold)
 
What pisses me off is when some people decide to buy new lab equipment because it would cost too much to send the unit for new precision/calibration
certification so they decide to buy new stuff and trash the old stuff but their rules are that product must be not operational to be taken off inventory... so they cut cable cord if you're lucky or they use a hammer on knobs or display in worse cases. 

I was going to have a couple of different tiers of PCs, probably the lowest end one with a 1st or 2nd gen i5 and an RX 460 for around $250 and then a higher end option for something like an i7, larger capacity hdd and a 1050 or 1050 Ti.

PCPartPicker part list / Price breakdown by merchant
CPU: Intel Core i5-6500 3.2GHz Quad-Core Processor  (£189.59 @ Aria PC) 
Motherboard: MSI H110M PRO-VD PLUS Micro ATX LGA1151 Motherboard  (£47.89 @ More Computers) 
Memory: Crucial 16GB (2 x 8GB) DDR4-2133 Memory  (£83.71 @ Amazon UK) 
Video Card: Gigabyte Radeon RX 480 4GB G1 Gaming Video Card  (£187.99 @ CCL Computers) 
Power Supply: Corsair CXM 550W 80+ Bronze Certified Semi-Modular ATX Power Supply  (£68.82 @ Alza) 
Total: £578.00
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-01-02 23:25 GMT+0000

This should be good.
Doesn't include wifi, but id assume you would have a solution coming from an existing build.
Could trade less ram for a better gpu (Well, "better" since the 8gb 480 isn't any faster than the 4gb). But thats up to you.

https://uk.pcpartpicker.com/list/c73Dnn  Less ram more Vram

You need to connect the 8-pin.

A 1060/480 are ahead of a 970 for sure. A 970 I would say is more or less closer to a 3GB 1060 and ahead of a 4GB RX 470

Whichever is cheapest, even if it only has a single fan. I have the Zotac 1050 Ti mini with a single fan and the temps rarely go above 50 Celsius, which is extremely low for a GPU.

Whichever is cheapest, even if it only has a single fan. I have the Zotac 1050 Ti mini with a single fan and the temps rarely go above 50 Celsius, which is extremely low for a GPU.

I don't know much about machine learning but I'll try to answer the questions I can.
 
1. It is usually better to go with fewer cores and a higher clock, just don't go below a quad-core. Some applications can only utilize one thread at a time so the extra clock speed will do you a lot more good than 2 extra cores. However I do not know much about machine learning so more cores and a slower clock might be worth it, I would do some research.
 
2. Your GPU will probably be fine, many people SLI graphics cards with consumer boards (Z170) which works just fine, SLI will always have some efficiency loss however so don't count on 2x performance, more like 1.6-1.8x.
 
3. If you want to SLI, don't buy a 1060, it is not supported. Keep in mind that a single powerful GPU is always better than two weaker GPUs so get the best single GPU you can afford now (you can still SLI later if you want to). Also, wait for another couple days or so to see how AMD's new graphics card performs. Might be worth a buy and worse case scenario will at least cause Nvidea prices to drop a little.

While the 660 is still very good, entry-level gaming cards like the GTX 1050Ti can now beat it due to the advances in architecture.  

I had a pair of 670's until a couple months ago. A single one of those is still very capable in games that aren't pushing the 2GB frame buffer to the limit.

Depends on how much cheaper. 1050 is $109 and is superior due to better driver support and newer architecture, but if you can find the 660 for half the price than it is definitely worth it.

Saw a post about whether the GTX 660 was still relevant and became curious. All answers are greatly appreciated.

Sounds like a great deal to me. Although the 4460 for £100 might be slightly better price to performance.

That's why I used a toaster oven. Bought it for $7 at Goodwill and have used it to fix the GPU and some RAM, both work great now. Worth a shot for $7. I don't use it for food.

I upgrade sometimes more than once in a cycle, IE: 980 to 980 ti when it came out, and probably 1080 to 1080 ti when it comes out if it's any good.
 
Although if the 1080 ti isn't as close to the titan as previous TI cards, I may just get a Titan XP used for ~1050 and sell my 1080.

Usually when my GPU gets too old, or when performance wanes in the latest games. though with a 1070 I don't expect it to be phased out for a year or two 
 
the exception being Vega. if it's any good i'll switch to that. 

You know, i actually completely missed those generations
I went from 6950 to rx 480, and the finewine stuff is already visible with the RX 480.
 
And tbh the 6950 probably kept up better than it should have done but i'm not complaining! Even when i sold it after having it for 6 years it was still doing IMO a decent job.
1080p60 on low/medium wasn't that bad actually, the only thing i could compare it to was a 560ti from a friend and my god was it a big difference during the last year we had them.

Ok, then any i5 that you can find for cheap would be a good deal, 4430-4690k. Definitely upgrade the CPU first, the 1050 is a pretty good card and I see no reason to upgrade it, at least for a couple more years. 

4K relevant while keeping the price down is going to be hard, if you're on a budget I would go with 1080p, it still looks fine, even a few years down the line it will still be a viable budget option.