I've ordered mine thru one of the major bearing supply chains (U.S. Bearing). Occasionally there's a back order, but usually the 2 SPF sizes are available in a couple of weeks.
Go to the Superformance Forum threads on this site, back to 24 Jan 2010 to a thread titled- Adjusting SPF wheel bearings-. That was start date, finished around July 2011.
Post # 92 has seal part #'s and supply agent. Read the thread, might help you!