There are times at our Goodwill and Salvation Army that you can get a bargain. But for the most part, you can find new items for the same price as their donated items. Our GW wants $3.97 for pair of children's shorts. I can go to JCPenney and pay that for new when on sale.
But DD did find Lexi a tri-cycle in excellent condition for $3.97 the other day. They just want something for her to ride at the park. If the Goodwill thinks it is an "antique" piece of furiture or a fancy brand name, then they put a high price on it.