Query on usage of Swiss pass for my itinerary

I will be travelling to Switzerland from 21-24 June. My itinerary is as follows:

21 June: Paris --> Interlaken
22 June: Interlaken--> Jungfrau --> Interlaken
23 June: Interlaken --> Lucerne
24 June: Lucerne --> Zurich

I have a couple of queries and hope someone can help:

1. For this itinerary, is it worth purchasing a 4-day Swiss pass or some other card e.g. Swiss card, etc?

2. If I were to purchase Swiss pass, can it be used for my travel from Paris to Interlaken? or shall I travel to some city in Switzerland (such as Bern, etc) then use the Swiss pass to pay for the travel to Interlaken?

Thank you for your prompt reply.

Can I check whether the price is fixed for Swiss saver passes (for two people with 15% discount)? I'm thinking to buy it only when I'm leaving Paris on 21 June. Will there be a chance that the Swiss saver pass runs out?

Hi whwhwh. No, there's not one fixed price. Prices depend on your country of residence, current exchange rates, the reseller you choose, whether offers are available (please review the first six topics on current offers in our forum topic overview), and so on. We've listed all this in the upper right corner of the Swiss Pass page. Just fill out your data for an overview of purchase options and prices. Please note that the Swiss Pass is not for sale in Paris.