I just made mine out of 3/4" galvanized conduit with a conduit bender. $45 for the bender and 3 pieces of conduit for another $18 (screwed up the bend on the first piece). Once bent, welded 8 tabs on, drilled some holes and voila. These aren't structural so not too worried about it being conduit.
Based on the way that the inner velcro sleeves fit around the 3/4", I believe the stock alpine bars are 1", but have been told by many that they are NLA for Tithonus'.
Didn't realize the added benefit of how much these bars reduced the soft top noise as well. Reduced it from an F3 tornado to a somber F1 noise level. And of course the soft top fits much nicer now with no sagging.