Check out
www.horizonbbqsmokers.com They are in Perry, Oklahoma but Im sure that they could get one out to you. I am building one myself. I shopped around and found that I would end up paying more than eight grand to get the rig I needed. Building it myself has saved me thousands of dollars. Im using 1/4in thick 36in pipe. Cooking area is 9ft long with offset 3ft fire box.
I patterned it after the old "Oklahoma Joes" trailer rigs. Im using tuning plates in the bottom of the cooking area. Runs about a ten degree difference from end to end of the cooking area. Entire trailer is over 20 foot long.