If you're going to buy raw on eBay, and you're not sure about the seller, ask as many questions as possible. Reputable sellers will usually provide scans of the front and back, and will disclose information, if you ask nicely. I'd personally look for raw books from boardies first in the Want to Buy section. There's a lot of sellers on eBay who overgrade books.
If you do find something worth taking a chance on (I.e. scans look good, etc.) ALWAYS ask how they package books, BEFORE making the purchase there's nothing worse than finding some high grade book at a decent price, only to have to return it due to poor packing