A lot of charity shops don't understand that, with books and records, the price you see an item selling for on ebay or amazon is not the same price as it will sell for in their shop.
The result is that they proudly display books and records for the same vastly inflated prices that amazon seller sell them for and the stuff stays unsold, get pawed and prodded by various people until they are in such poor condition that they are worthless.
I have seen this happen to books on countless occasions and I find it depressing. I'll make them an offer, a reasonable offer at a price that enables me to make money too, for the book but usually they insist on their "researched" price. A couple of months later and the book is, unsurprisingly, unsold, then they ask if I will give them however much I offered only by now the book is in tatters, so no good to me or anyone else.
The fail to understand that when an item sells on ebay for £75 it's because 2 or more people on opposite sides of the world really really want it and are bidding on it in competition with each other and that it is unlikely in the extreme that anyone of those same 3 people will travel from Australia / American / wherever to spend an hour in their messed up (and sometimes very smelly) charity shop looking for that rare record of book that they have always wanted.
I think that they should do their best to research the true value of the items, of course, but they need to understand how the real value of a book or record is established and to appreciate that people will pay less in a charity shop then in a top end boutique / record shop / book shop.