The engines are no longer available from Herbrandson, the military program they were made for is no more..They are a few surplus engines around, you might sometimes find one..We (racers) have mostly used up the few we had...The carbon props we use cost $10 per diameter inch..We use 23x27 props on the racers...
I have 2 new cranks and cases left and could make a new 280cc version for about $2500.....
One of the racers might have a used one, I will PM a message with a website you can access if you want to try to get one that way....