An alternative is to go with an online purchase from a company that's good about doing returns. For example, ULA packs are sold almost entirely online, I believe, so they have to be good about this. I'm personally a fan of ULA packs, and have bought from them that way a couple of times.

This approach can work with other companies/products too, but you do want to have a good idea of what you're looking for in the first place and look for a very good and easy return policy.