What metal to use for roof rack?

Ok so I am planning on making a roof rack in the next few weeks and here is the thing; I know crap about welding and metals and all that rot.

I obviously am not going to weld it myself (I got a few buddies who know a thing or two about welding) but I need to know what metal will make a good rack. I am going to use 1x1 square tubing to make it and I will be powdercoating the entire thing (for free too!) so rust isnt a big worry.

I found this site which has all types of steel http://www.discountsteel.com/products/Stainless_Steel.cfm?PAGE_ID=1 and basically I just need some suggestions from someone who knows what they are doing.

So what should I use to make this roof rack?

AL, If your buddy can Tig! (there is also a rod for stick welding AL, but I have never seen it come out looking decent)

You want to keep the weight down. A steel rack like that would probably weigh eighty pounds or more.

I would reccomend 1" .065 wall square for the bottom "floor", 3/4" .065 wall square for the sides and light bar part.

You don't need that much metal around the lights either.

I agree, don't need that much metal around lights. That is a lot of cutting and welding for something unnecessary. If you really feel like they need that much protection throw another piece of expanded metal in front of them, or some plexi or something, but most lights are pretty rugged. Also, maybe not so much support all around basket, less is better on top of your vehicle. Your mounts will be the weekest point, so don't over build it.
As per your question, there are some dudes building baskets out of conduit all over the web. Check out some of the "tech" stuff over at cherokeeforum.com. There are some good ideas for racks over there. Most of all keep the weight down though and really think through what you will put up there. I hauled 3 dead deer in November on my rack. It is a Surco and built out of Aluminum. I screwed it together and the rest is riveted. I have also hauled camping gear and my tire up there, but you learn pretty fast, weight up top sucks, so go lite.

I am actually figuring some thing sup in my head also for a homade roof basket. I am looking into using eletrical conduit to make the main frame for its galvanized finish, and also for its light weight atribute, and very low cost. You can get a piece from Lowes for 3 bucks for a 3/4" x 10 feet piece... I was going to use some mild steel cross hatched for the floor and also for the uprights on the sides of basket... Just my 2 cents...