I checked out the two nearby music shops and one of them is shutting down (no 'ukes, but if you need a bust of Franz Liszt I can help you out), and the other, the one I mentioned previously, has a few toy-like 'ukes (or at least they seem so to me). I also checked online and found several music shops between Lausanne and Villeneuve (figuring Montreux, home of the Jazz Festival, might have something, and it's a lovely trip from Geneva), but NONE sell 'ukes. Can you believe it? I found one that sells tubas, but I don't know how your Mom will feel about that.
Oh, I changed my strings, finally, and it sounds worlds better but not holding the tuning as well as I'd like (after a week). I'm sure it will settle in soon.
So sorry I couldn't be more help! Maybe you could start a thread and see if anyone knows of any decent shops in Zürich or Bern? Let me know if I can look into anything for you.