The cheapest and best source for parts for the Ion and Micron is Alesis themselves. They only sell parts and ship to USA customers though

Alesis Parts Department - Phone: 401.658.5760 x1407 or send an Email to:

They usually reply to emails in a day or so...

There is also Intrumental Parts for non USA customers. Typically the parts are much more expensive though. Here is the link for the Ion:

Here is the link for the Micron: