I think you're misunderstanding my point - I don't have any issue with giving things away for free to someone who'll make good use of them. And I especially don't mind giving someone a good deal on something.

What I mind is going to a for-profit thrift store that will give me a dollar for a $40 appliance. If I'm going to sell something to a store, I'd like a half-decent price.

But to quote your own logic - "try thinking about your own post." What's wrong with wanting to sell something for a "Half-decent" price? For all you know, I'm barely making ends meet. Instead of presuming to think that the buyer is entitled to a great deal, try considering the seller's situation and whether they might deserve more than 1/5 what they paid for something. You can "look out for folks that you see" too - by paying them appropriately.