I haven't seen the foam ones yet. I have one of these from Aerotech.
http://www.aerotech-rcmodels.com/Pro...ick/stick.html
The Aerotech are fairly large at an 8" wingspan. I also bought several of the Hangar 9 mini airplanes from this place for $2 each. Scroll down the page a little to see them.
http://members.tripod.com/aaron686/id42.htm
Just cut a slot in a small dowel and then glue the rudder into the slot.
I've also seen some people with planes made out of carbon fiber, but I'm not sure where they come from.
Good hunting!!
Dean Bird
Sun Valley Fliers
Phoenix, AZ