All said and done, minus the kettles it came in a litte over $2K. However, that's with shipping included and most stuff I had to mail order. I also ended up buying some plumbing pieces that I thought would work and didn't, so I had some waste added in there.
The killers were the Baso pilot safety valves, around $150/each. If you're not worried about the pilot and burner blowing out and will always be around when you are brewing to monitor it then you could leave them out, but I would rather be safe than sorry so I included them.
Little stuff like the quick disconnects, general hardware (carriage bolts, drill bits, angle iron, washers, etc) add up too. I have all my receipts so maybe I should post a general parts list...
I don't think there's a cost savings to doing a wood version vs. a steel one. It might even be more for a wood frame since you add in hardware, heat shields, and paint/stain/lacquer/brushes/mineral spirits. In the grand scheme of things the frame cost is nothing compared to all the extras like gas system, electrical, plumbing.
Rob