Every year on my birthday, I treat myself to an unreasonable purchase. Something that I always wanted but wouldn't just buy it normally because it wouldn't be practical or reasonable. Something like an expensive toy, or a fun gadget, or a hobby kit.
This year I'm indecisive between the Steam Deck and the Meta Quest 3. You might ask why would that be unreasonable. Because I have a family with a newborn now so I don't have much free time to game anymore. It would be a waste because I can only play like once or twice per week.
I would love to hear about your desire for an "unreasonable purchase" (within your budget).
A 3D printer. Had one a while ago, stopped using it because it had a few issues (baseplate wouldn't adhere to prints which would cause pretty bad warping, the 2 z axis motors would desync and cause the head to get misaligned, the motors would jam, etc). It would be pretty unreasonable to purchase one, most of the projects I'd like to try would also require spending money on electronics, a soldering kit, and mechanical parts. I don't know if I'd ever have enough time to do that type of project from the ground up.