Just yesterday, visited the recycling center looking for throwaway laptops, (as if I didn't have enough already) I was looking through the thinkpads, x230s x220s, etc etc all like $70 total. My mom says to me "Are you sure you want a thinkpad?" so I go to the other systems, lots of old HP stylus things that were total junk. But then looking through the piles of junk Dell laptops I find this. A Latitude e6440, now just seeing the core i7 sticker and the $40 tag of course I needed to test it. I ask to test it because they let you do that at this place before you buy. I put ram in it and plug it in (didn't know the battery was functional) it boots to bios, good enough for me. So I buy it for $40, $5 for a power brick, $10 for 8gb of ddr3 sodimms, and $18 on a 500gb hdd. Given it's a dell from ~2014, the hard drive didn't fit. I go to another machine and swap the hard drive and the 120gb ssd from it. When I get home, it will not boot for whatever reason (ram speed or something the 1333 stick wouldn't work at all only my 1600mhz ram would work. No big deal $5 loss. Install windows 7 and use the key that was included under the battery. Working good! Best part is, it has a core i7 4600m, 4gb ram, 120g ssd, and an AMD 8690m GPU. Not the best but could have done a whole lot worse. Also has a backlit keyboard.
Recap of expenses :
$40 parts laptop
$5 working ram
$5 bad ram (loss)
$40 ssd
not counting hdd because it wasn't used and is used in other system now.
Benchmarks in a few minutes