If you're selling stuff on eBay, it can be hard to know how much it's worth. Redditor outfoxthefox notes that you can actually search eBay's completed listings, so you know how much similar items sold for.
To do this, just search for a similar item on eBay and scroll down to "Show Only". Check the "Completed Listings" box, and you'll see all completed auctions for that search. Items with green prices sold at that price, while items with red prices didn't end up selling. That should give you a good idea of how much to post your item for. Old eBay hands will doubtless be familiar with this trick, but it's worth highlighting for less experienced users.
Of course, you can also check out WorthMonkey to see how much your item is worth, but every site is different, so this technique can help give you a more eBay-specific idea of what's selling.