Last year I bought an air purifier for ~800, but PLN ($1 = 3,7129 PLN at the time of writing) to deal with the Polish winter - already swapped out the HEPA and carbon filter(<$40 total cost) because the air coming out started to smell bad(four days of 120ug/m3+ smog with peak at 200ug/m3 tend to do that to filters).

At a CADR of 300m3/h I think the price/value ratio is decent, as opposed to whatever Dyson is trying to con people into buying.