https://cleanaircrew.org/box-fan-filters/

Cost: one fan, four air filters, duct tape.

Purifies better than any commercial filter, never stuck with being unable to find a replacement filter.

Very expensive… But the Nuwave is very nicely built and nearly silent on the lower settings. It comes with enough filters to last you 5+ years. Replacements after that seem to be $20 each, and they last a year.

I don’t use the wifi function, but it’s a thing.

The price has gone up a lot since I bought it. Would be hard to justify now.

Coway Airmega for most people

model AP-1512HH