Have a look at
First Quality Music

"FQMS SuperCases are built with seven different foams and plastics and a three-ply waterproof fabric exterior. The result is tremendous impact and thermal protection in one of the lightest packages around."

I use one for my guitar. It's not as impact resistant as a Calton, but it's about a third of the price, and has much better thermal protection--which to me is much more important than impact resistance.

Rich McCarthy