[Fyron]

If a part comes to you and it doesn't work, you can return it just the same. Unless you are buying parts from extremely shady dealers, you are usually ok to return them without even considering going to the manufacturer directly. Newegg.com, for example, has a 1 year replacement policy for many items. Some items only have a 30 day replacement policy, but that's surely enough time to see if anything you bought came broken.

It isn't difficult to buy a case that is easy to work with. You are more likely to get a cramped, crappy case from a whole PC vendor than when you have free reign to choose one yourself.