Here is a card that has some semblance of proper market evaluation. Goldspan Dragon is going to be really good in all constructed formats.
The main selling point is the ability to make 2 Mana out of a single treasure token, which is super strong. This is a major foundation for a huge number of combo decks in modern, legacy, and commander.
On top of that, it has Flying and Haste, which makes it a solid threat. Goldspan Dragon is more likely underpriced at this point, and there is a chance for it to go much higher than $15 a piece.