Both Menz and Fly-Tec makes quite cheap multiblade props. Both up to about 33in 3 and 4 blade.
Example: Menz 32x18 3-blade 97euro (about the same amount in $)
Fly-tec 33x18 3 or 4-blade 134.90euro.

So if you can live with the fact that the prop does not have the exact scale blade shape there are many sizes to choose from. How about a 28x3,5... Talk about slowfly...

http://www.hoellein.com/websites_neu/home/home.html
http://www.fly-tec-modellsport.de/we...hp?artgruppe=1