Don't mess with the Rusty's.... I've tried to get some more info about that lift, and they give me the run around. Just doesn't seem like the have it all squared away quite yet. BDS makes a 4" lift also.
It's a one off, any 4x4 can build you anything you need. There is only one Comander i know of with 37's It's the ice something...
Going with 37'' tires will put so much stress on the front and rear diffs. It's so much work to go bigger since you need to re-inforce everything to handle the extra weight and angles. $7900 sounds about right thought.
this is the only WK / XK style vehicle i know of on anything bigger then 34s
this is sitting on 39's - but to do so they need to stretch the wheel base and pull the back axle back to avoid cutting into the doors for that size tire