Actually I saw a cage that was put together by David Wilks, and it was the most beautiful and well done cage I have ever seen.
I don't know what Dave is doing nowadays, but if I were in his area, I'd strongly consider having him put a cage in my car either while I waited or buy the parts and have it installed locally. I've read alot about cages - what to do and what not to do - David's cage was done right - no expense or time spared in it's construction.
Like him or not, the guy knows his stuff.