I also had to get these filters and tracked them down to the folks who bought Rush-Hampton Industries; namely, TekQuest Industries.
Contact info is as follows:
4200 St John's Parkway
Sanford, Florida 32771
Pricing for the filter element is:
$5.35/each up to 10
$4.60/each for 11 or more.
$3.86/each - 50 or more (case = 50)
Filters - Beige or White
Part number for Beige element = 15566
Part number for White element = 16407
and you can get new units too for with fan and motor and cover for $21.96. They call this the "B-Pack."
I talked to a woman named, Leslie, who was very helpful.
They have another site where you can buy on-line, but that site doesn't show you that you get a discount at 10 units. That site is: