>it uses the powercup concentrators much faster than stated.

I've found a local source for these (cheap!) but it's a regional
chain so it won't do you any good unless you happen to live in
Wisconsin, northern Illinois, or eastern Iowa:

http://www.farmandfleet.com/storelocator.asp

$.99+tax for 8 pcs works out to about $0.13 ea.

Oddly, they don't seem to actually sell the Powerpop (maybe
they're just sold out?) but they do carry other stuff from
Presto.

I have no connection to the company other than having grown up
within walking distance of one of their stores...