Syntactic foam

I recently ran a sample batch of Loctite's "Synspand" syntactic foam. We used it to provide consolidation pressure in a closed composites mold, where we would normally use an elastomeric bladder. It is basically an epoxy matrix in sheet form with micro-encapsulated foaming agent. It worked great, but then we got the price list from the distributor. This stuff is over $200/lb!!! Anybody have any experience compounding their own heat expanding foam for closed molding pre-preg composites? We are trying to acheive a min. of 100 psi at 250f for a min. of 30 minutes. Low final density is prefferable. Any advice out there? Cheers - Alex