what are you talking about $25??? Its $6 CDN for a 2' x 8' sheet at home depot, or was when I bought it, and I actually managed to find some mis-cut foam in with the mis-cut wood, for $2.
find a construction site and tear some off the houses
just cut out what you need, and leave a little note and a few dollars behind.
Yeah man, I went back for more and looked again. The pink stuff is NOT cheap, not around here anyways. That's okay, I'm doing just fine with the white stuff... it makes a mess, but nothing like some of the stuff I work with. My last major project has been building a fiberglass interior for my car... man, sanding fiberglass and body filler with a power sander makes a SERIOUS mess

Anyways, on with the update!