I entered the ISBN number and received quotes from several companies buying books. I used two of them. This site offered the most money for one book that others offered significantly less. I therefore selected them and mailed off the books. The other site had the books processed and paid within a week. Sellbackyourbook took almost 3 weeks to get back to me and then said they couldn't pay for the one book because the number was wrong. However the other sites also had this exact same book listed so I am not thrilled with losing out the money but it wasn't worth getting it back and trying again.