They can't give you an estimate because it will take more time than they could ever think to get it done to your expectations.
I would suggest what someone else did.
Get the bottom sandblasted and frame cap it. Buy a welder and practice or get someone who does weld to give you a few pointers.....it's not hard really.
I bet you dimes to dollars you will spend 1/10th of what the body shop would have to invest to get it done yourself. Just be careful and unload the suspension before you get in there and start cutting and grinding.
Good luck.....there all worth saving if you love them.:love7: