The price on the SBB (Swiss Federal Railways) site is the correct price, direct from SBB, whose pass it is. Same price for buying at a stations as online:
Adults.
2nd class 1st class
3 days CHF 210 CHF 336
4 days CHF 251 CHF 402
8 days CHF 363 CHF 581
15 days CHF 440 CHF 704
If you buy the pass indirectly from anyone else, especially if they quote you a price in some other currency, it is likely that a mark-up has been added.
How are you getting to Zürich? If you are flying in, then you will be wanting to get your passes from Zürich Flughafen (=Zurich airport) station, not Zürich HB in the city centre.