Wow, TIL — homemade CNC for under $500! The same project also covers homemade 3d printers.

Are there any other projects similar to this, making normally-expensive pieces of equipment approachable for hobbyists?

PrintNC is the next step up from MPCNC. It still needs some 3D printed parts but is mostly locally-sourced steel profile and electronics bought from Alibaba: https://wiki.printnc.info/. Last time I looked the parts cost circa $1000 but that was a few years ago and I expect inflation has probably doubled that.