If I buy a copy of Microsoft Office 2007 and never open it, would it be possible to resell it on eBay or bring it back to store, or do something of that nature?
If it's never opened, sure. Most stores won't accept returned software that's been opened. If you eBay it, just be clear in your choice of words when you describe it as being new, sealed, and especially unactivated. If they suspect you're selling an OEM/bundle copy, or a used copy, they'll usually shut down your auction.
Although it sounds like you're planning to buy it with the intention of returning it, which begs the question... why???