These props on ebay in the USA are 18 " + 19" diameter. The P22 prop is 16 3/4 " x 21" pitch. Normally it is called an 807R. The only reason that i can think of that they are so expensive is the fact that there are probably few sold compared to volvo and mercruiser etc legs.
They can be found from time to time, this one just went tonight on ebay!
The 18" + 19" props are for the 103 and 113 series legs, so be careful as they wont fit a standard P22 (101) leg. Likewise some of the parts in the USA on ebay, it doesnt quite feel as much as a bargain when you pay as much again to get then posted and they dont fit. duh..... its a long way to send them back!