lets not beat around the bush here.
Your not only going to need add some flare to your builds to grab peoples attention you'll likely have to sell it at a loss because your not established.
Your going to need to be able to source the parts, probably in bulk. You'll need a website and probably a business address, you cant have your home address on your website. You'll likely have to hire HTML coders to build your website to a certain standard, then you'll need to be able to ship the thing, what are you gonna do if something breaks. You'll need to provide a warranty.