You can use PD (Pure Data) in stead of MAX
It's an open source alternative to MAX developed by one of the original MAX developers.
It's not as advanced as MAX, but it's constantly being improved. I don't have much experince with it myself, but i know quite a few people who do and i Think the consensus is that it is easy to use and quite capable.
It's available for Windows, MAC, and serveral Linux variants including Ubuntu.