Resin Casting

I have been looking into this for awhile and was mainly scared off by
the price of resin.

For a 'small' package of Alumalite brand it would cost be almost $30.00!
 I am not sure exactly how much that would work out to for 25mm stuff. 
But I was intending on casting a few custom vech. (I made out of plastic
'trash') and a bunker.

Anybody have a good source for CHEAP resin supplies in the US?

Thanks,
Scott