Amway's air purifier cost RM4k ! It has a test to compare with ionizer and if I am not wrong  the speed to filter the air is almost 8 times faster.
Good price, good quality.

The calculation should be in this way.
Buy 1 good air purifier with 4k and its performance is equal to 8 normal air purifiers.
But if you buy 8 normal air purifiers, the price is about RM700x8=RM5600
It's still worthy to consider to buy 1 good air purifier, right?

Also, you must bear in mind that the function of air purifier is to filter air and to provide clean air to breathe. As what I had said, if you buy a normal air purifier which fails to filter air fast enough to let you breath clean air, why waste that money? It's unless every time when you want to breathe, you inhale very close with it and that seems impossible.

Oh .. is it ? Actually I heard that info from a friend of mine. It seems he told me the wrong thing. Sorry. 
Then, forget about Amway. Buy Sharp. Good luck.