There are great bargains on eBay for Italian, Russian and German piano accordions, since accordions were really popular in the '50s and subsequent generations find them in closets and don't know what to do with them. I'm by no means an accordion expert, but from the research I did before I bought one, I got the impression that older ones are much better made than current models. Hohner accordions are apparently top-notch.

I made the mistake of buying a 120-bass accordion when I was just getting started and it was daunting. With no experience, I couldn't begin to figure out the bass buttons. And the more bass buttons an accordion has, the bigger it is, so mine was gigantic and cumbersome. I'd recommend starting out on a 26-key, 48-bass accordion, since you wouldn't have to use all of the bass keys when you're just beginning, yet you'd still have room to advance. When I realized I'd never learn to play if I hung onto my 120-bass accordion, I found a great used 48-bass one on eBay for about $60.

Sorry I don't have much information, but I've only been playing about a year. Very cool instrument, though!