If you have a metal supply store in town it might be cheapest. We have IMS in Los Angeles that is great for this sort of stuff.
I made the wind deflector out of aluminum that was 6" wide and I think something like 1/16" thick. It was like $20 I think
Consider getting 3003 aluminum. It is...
At the front I have an extruded aluminum cross bar that is at the same angle I cut the front of the side bars. I'm using some t-slot nuts and bolts, and I just drilled holes through at the right location. I can get a better picture this evening.
I got the crossbars from here: EX-1020-BLACK – 1″ x 2″ Smooth T-Slotted Aluminum Extrusion – Black Anodize – NEW | TNUTZ
For fasteners, go to McMaster and get two packs of 97763A267 (black stainless bolts) and one of 96765A140 (washers)
The side aluminum (2"x1/4" two pieces 8ft long) I got from...
I needed a new roof rack and while I like the CBI/Prinsu style it is just way too expensive for some laser cut aluminum and T-Slot bars.
So I made my own; it took about half a day and cost me around $300.
So far it works great! I'm happy to answer any questions.