Since I'm a small shop, I typically drop-ship alot of the new and large parts right from Alesis, so to answer your question, anything they sell, I have :-)
I sell everything I get from them at MAP, which is $89. Currently, Alesis doesn't have any separate mounting solutions for their cymbals, but I carry Pintech arms and clamps, as well as the full line of Gibraltar products.
I'm working on getting the Gibraltar stuff online, but with almost 30k products available, it's a tedious process. :-)