As luck will have it, I found these guys locallhttp://www.austinfoam.com
They use polyethylene black foam material (1.7 & 2.0 lbs), and charge just $12 per insert.
On request, they can also cut a logo on your top insert:
Notice the tapered edges on those middle inserts (for a Pelican 1750 case).
Ask for: Bo Shearer - Packaging Designer.