My son had me pre order a xbox game one time for him from Amazon. We end up getting it the same day the game first come out in the stores. Some of his buddies drove a couple hours the day the game was release to get it at the store, not us.
A few days or couple weeks later (don't recall for sure) I get a email from Amazon about the xbox game being cheaper now then when we pre ordered it and that they refunded us the difference.
I have found returning things through Amazon extremely easy to do too. Most often once the tracking number shows my return has been picked up by UPS my funds for the return are credited back to me that same day, before they even receive the return.