A good quality belt. A cheap belt may last a year or two while a good one lasts decades but doesn’t cost 10x as much.
Any sort of micro-mobility device (bikes, scooters, etc. or even costlier electric versions of these) that replaces a regular commute has good ROI over driving or even public transit (unless you’re lucky enough to live in a city where it’s free).
A big sack of rice. It’s kind of insane how many meals you can get out of one of those.
I just started looking into getting a recumbent bike, and holy shit does adding pedelec features skyrocket the price. I knew it would be a bit expensive, but goddamn ðŸ˜