Oh, thanks for the tip on increasing the price of a book to cover the shipping! The cookbook that's going for $25 is VERY BIG and VERY HEAVY....might be part of the reason those books are going for so much.
It also makes sense not selling books for less than $5 because of the cost of your time, and now gas to get to the post office. Maybe for those under $5 books I can list several at a time on Ebay, that way I only have to go to the post office once.
Thanks for all of the help, everyone.