DIY corsi-rosenthal boxes are cheaper than commercial air purifiers and easy to assemble with duct tape. (Color/patterns with duct tape add some fun looks.)
https://en.m.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box
High static pressure PC fan boxes are more expensive but quieter, fit more unobtrusively in rooms, and with lights ... look cool.
https://itsairborne.com/building-a-pc-fan-corsi-rosenthal-box-68e7cd1ca570
See also
https://cleanaircrew.org/
https://cleanairclub.org/about
https://www.cleanairkits.com/