You can get a pi zero w for $10
https://www.raspberrypi.com/news/supply-chain-update-its-goo...
I get that the Rpi will use less power, but I imagine many people will be like me and have it overclocked to 2.1ghz, and my heatsink was pretty warm all day long.
I've recently picked up a Optiplex 3070 with a i5 9500t for $120 and bought 32gb of ram off ebay for another $40. Considering a Rpi 4 is going for $100 on eBay, it's not a bad deal at all.