I've purchased many very cheap used books on Abebooks. Most arrived without an issue. The problem is that if the seller fails, you have ZERO protection, your money is gone forever. So just spend money you are willing to lose, Abebooks will not help you at all.
My last purchase was 20 days ago, seller "Ergodebooks" will not respond after my book didn't arrive, so no book and no money back. I'll take that $12 loss, no big deal, but still a waste of time and effort.