Is there any cost effective alternative for RC plane foam wheel?

You can use cheap carrom coins with foam tube cut into slices... Definitely it is not as light as foam wheel. But it will work if you manage to put a hole in the center of carrom coin without breaking it...

You can use the wheels of an old toy car or truck.thats what i use

fiber carrom coins are also available in the market. they too are light weight.

Core of 1/8" balsa disc, sides of 1/16" balsa discs of slightly larger dia.
Tyre of fuel tube, ends stuck with CA.

Not an alternate for foam but it is foam    ,These wheels took a lot of beating still good ,reply # 53 www.rcindia.org/electric-planes/my-favorite-plane-so-far-slow-slow-slow-flyer/50/