I bought a refurbished Stages single sided crank arm power meter in early 2020 from Pro's Closet for $130 out the door. It is an FSA Energy arm that replaced my stock FSA Gossamer (yes, I run the Energy PM arm on the left side and the Gossamer arm on the right).

It's been rock solid, zero complaints. I'd prefer dual sided, but... $130. I would highly recommend. I've been looking for a Cannondale Hollowgram version of this same PM for my other bike, but they're more like $400, which is still pretty cheap I suppose.