Umm... I sold many many textbooks thru eBay and I always shipped thru priority because as a student, I know how important it is to get the book within 3 days rather than a week or even more if its coast to coast. People are willing to pay the extra $$ if they know they'll get the book fast with priority mail. I often ship paperback books in the flat rate envelopes (most paperback books, even paperback textbooks, will fit nicely) and I've never received any complaint from buyer with my method. For hardcover books I usually just use the flat rate box and charge $10 for shipping since most other sellers charge just about that amount anyway, so you're not overcharging. I really hated one seller that charged me $8 but sent the book via media mail, it was the slowest POS ever and delayed my reading for 2 weeks. So please don't ship only via media mail, you'll get complaints. Offer various shipping methods like media mail, parcel post and priority and let the seller pay the shipping amount they want.