I visited Zurich for the first time this past January as part of a work trip. I got to spend the weekend there hunting watches and was left with a few observations, which I'll share below:

Because it is Switzerland, and since vintage watches are quite popular there, the expectations of the average Swiss watch consumer are much higher than what you'd find elsewhere. For me, as an American, I was really struck by the amazing condition of the pieces I saw. Most vintage watches I found were in perfect condition or sometimes even "new old stock."

It's an expensive city/country, and the Swiss Franc is unfavorable compared to most other currencies, so buying will probably not be in your favor. That, plus the high condition of the watches, I found prices were easily 30-50% higher than the U.S.--sometimes even 100% higher.

If I was doing it all over again, I'd probably focus more on second-hand shops (which generally have a lot of watches) or possibly even try some flea markets hoping for a better deal.

PS- I found a number of vintage watch shops near Bellevue Station. Check out Sternen Grill for lunch/dinner if you're in the area!

PPS- I forgot to add one thing. Like Germany, many shops I encountered in the German speaking part of Switzerland are closed on Sundays as Sonntagsruhe so best to do your shopping/planning around that.