I just found this company whilst surfing the web.
http://www.puch500.at/default.htmThey are an Austrian outfit supplying parts for Steyr Puch vehicles. It turns out that they made a version of the Fiat 500. They also supply parts specifically for the 126.
Their website has an english translation (just click on the union flag on the left), and they accept credit cards.
I haven't used this company as yet, so I can't say whether they're any good.
If anyone does use them to buy parts maybe they could let us know how they get on?