Hi Glen:
I've never used one. I get mine checked at my Endo's.
Actually, from what I've seen in stores $99.00 is a decent
price. Costco doesn't sell them. The lowest price I found
on the web was $106.(that's 10% off for March).

And $116.00. I think those are the ST.
Ebay only has the $500.00(PO) one.
Sorry 'bout that. Maybe someone else knows of a better price.