There don't seem to be any measurements for that bracket. I'm skeptical. If it is dimensionally too small, the amount of weight it will hold is going to be compromised pretty dramatically. Frankly, I think you're better off fabricating your own somehow if the Axiom ceiling mounts are too expensive.

I have bought quite a lot of stuff from Monoprice and had really great luck EXCEPT for a pair of speaker brackets I bought. They were plastic, though, so may not be applicable to your situation.

bibere usque ad hilaritatem