Yeah man Saigas are everywhere! They've grown in popularity pretty steadily thanks to their mix of good price, solid performance, the ability to upgrade and personalize them, and what I've observed to be good reliability. I've actually got a .308 myself.
There are plenty of places to buy Saiga parts and magazines online including some Saiga-specific forums. A Google search will turn up most of those. You could probably ask for Saiga parts and magazines at a decent-sized local gun shop too. I think the place I used to visit was Saiga-12.com or something like that.