Love this thread - too right on keys and postcards, two of the things I collect outright.
I would also recommend a little site called
Listia, if you've not heard of it. It's basically a barter platform that works with a currency system of points. Good for trading random doodads for...other random doodads. You can purchase points for cash, do surveys, or just start listing items. I think they give you a certain amount just for signing up, IIRC. A lot of the sellers use it to offload lots of items that they have had trouble selling for cash on other fronts. Craft supplies, like those listed here, are widely available, both individually and in lots. Some sellers charge shipping, but most of it is usually shipped free, especially small things that mail easily. You can end up transferring the points to cash in a sense - things like gift cards, download codes (for games, etc), and postage stamps are big sellers. Play your cards right and you can end up at least replenishing the shipping supplies (stamps, envelopes, bubble wrap) you used to move the merchandise.
I unloaded a big tupperware full of bottlecaps that I had been hoarding for some time for a good chunk of points, and have been buying all sorts of little odds and ends for my collections and crafts with them ever since, things which I would normally have passed up if I had to pay cash for them.
There are lots of things like small electronics for sale, which you could essentially get for peanuts and might make a profit scrapping.
Might not be useful for everyone here, but it's definitely an avenue to check out.
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