Interested. Primitive Racing will build one, probably in the $200-250 range for 1/8" aluminum. Team O'Neil will do one too, but I heard the price was high.
A buddy of mine was talking to Tim O'Neil a couple weeks back, his suggestion was looking overseas. I took a quick google search, and it's looking like $150 or so for stamped steel. He also said to make sure to ad cooling holes near the back for cooling.
I plan on doing some TSD rallies, and need the underbody protection.
For the rear, all we need is some HDPE or UHMW-PE as there is nothing mechanical (ie. rear diff) that needs to be protected. Lots of rally guys use it as tank, brake/fuel line, control arm protection. Even flaps under to protect from gravel spray. Rally Armor uses it for mud flap material.
I plan on fabbing up my own aluminum skid plate, and will share the dimensions and build.