I just want to make sure this is legal because seriously thinking about building my own hackint0sh dirt cheap and sell them on eBay with a hefty profit.
You will likely not get in any trouble besides having a hard time upgrading doing this for yourself at home.
For several reasons, legal and practical, you do not want to resell them. The first reason is that Apple has a lot of incentive to protect their baby, and they will slap you around if you mess with their revenue stream illegally. The second reason you would want to avoid doing this, is the upfront cost. You will be out a lot of money for equipment, and $130 per copy of Leopard (you were not thinking about not including an OS disc, right?). The third reason is support. You would be selling computers that would break with every point upgrade, and you could bet you would be hearing about it from your user base. People that want to save money by buying a non-legit computer, yet do not have the know-how to do it themselves are not people you want to be responsible for supporting.