There is a counter at HPB and they will appraise them and possibly give you money back.
Go to the counter where they buy books. I've found that the amount they offer is generally pretty low, but that makes sense. My guess is they offer about 1/3 of what they'll sell it for. Outdated textbooks might not bring a lot. Still, it's better than throwing them out.
If you want to sell them, HPB will ask you to wait around until they can value them and make you a cash offer. It could be worth your while! All HPB stores have a buy counter.
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