This could be something that you bought for a higher price than what most people would guess based on the item, or it could be something you bought for a normal price that has gained significant value as time has gone on.
What made me think of this question is a LEGO minifigure I got with my “The Hobbit: An Unexpected Journey” disc. It is Bilbo Baggins in a blue coat that was apparently only sold in that movie box only at Target stores. Even considering the exclusivity, I would have guessed maybe $10-20 for such a tiny piece of plastic, but there are sold listings on eBay from $80 to $225. I could possibly even get towards the higher end of that number since I still have everything in the original box in good condition. It’s not worth a ton compared to some other items people may own, but I think most people would not expect nearly that amount.
It’s by Le Creuset, and they apparently rotate out most of their colors. So you can still buy the same teapot in a different color, which is what I ended up doing for my friend. The one I got was a limited run, it’s a pretty rich purple they called “cassis”, if you search Ebay for anything in that color the prices are nuts!
Red currants :)
Edit - apparently they are black currants. Still tasty!