Do you actually have to have new foam? I reuse most of my foam when I restore my seats. The only time I use NEW FOAM, is when it's beyond repair. You can you a rebuild kit, which will firm it up. And there are several options for that.
http://www.stockinteriors.com/jute.a...=31&ModelId=88
http://www.lmctruck.com/icatalog/cc/full.aspx?Page=74