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.
Geese. We got them to cut down on the number of chickens that hawks were taking. They live exclusively on grass so they cost nothing to maintain. We haven’t lost a single hen to hawks in the three years since we got them.
So that’s all about saving money. Where is the profit? Goose eggs. In the spring they lay eggs that are 5.5 to 7.5 ounces each. Chicken eggs are only 30% yolk. But goose eggs are 50% yolk. A single egg has a yolk almost 3x the size of three chicken eggs. These are worth money as food at $7 each or as hatching eggs for barter with other homesteaders that want geese and have incubators.
Edit: forgot to add that they are the best lawnmowers ever. They have dramatically cut down how much we need to mow. Which saves fuel and W&T on the mower as well as time.