You would think it's a standard pipe/rod with a boom or cymbal attachment at the end that many music stores would stock or be able to order. If you happened to be in Ottawa, Canada or nearby, I just got one back from my buddy's place where I have a DIY Alesis set built up.. I don't think I'd be using it anytime soon and could sell it to you.
I tend to drop into one of our local small business drumshops.. the guy has all sorts of hardware he stocks, and there are always a few boxes of arms, booms etc that he has for a few bucks if you're just looking for a part.