Well, I just got word that the stock I'm looking for is in.
Originally I wanted to go with an 3x8 rect. tube, but I woulda needed to order a 20ft piece, so I decided to scale back to a 3x6. Both 1/8 and 3/16 are available, but I have not decided on the thickness just yet. When I pick it up tomorrow, I'll choose.
I want to get mine powder coated, but thats probably gonna add $150-200 to the project!