CS>anyone know how to make a negative ion air purifier?

[Siriusss]

they are outrageously expensive and fragile and I dislike the dealer I  
bought the last outrageously expensive "flair" unit from.
 
I understand the directions are as easy as making a CS generator and it can  
be made for under $50 but I lost the bookmark to the instructions.
 
Anyone know anything about how to make one?
 
Harper