I'd say it's a good time of year to go, weather wise. It should be warm. Unless there's a Europe-wide heat wave, it won't be too hot. At least not for me. It's not even southern Europe, it'll be hotter in Spain, Italy for instance and I wouldn't avoid those for the weather either.
I would agree that Swiss hotels are expensive. Everything is expensive to be honest. You need to factor that in when planning. If it's an issue for you then all the neighbouring countries are cheaper but they're also very different.
The only thing that can be good value in Switzerland is the train - buy a half-fare pass and it is suddenly quite affordable. And they have a really good train network. We've toured all over by train.
Also, to save money, in most cities your hotel will give you a free local transport card. Not all unfortunately, but a lot. They will usually give this to you when you check in. It will also get you discounts locally for food, attractions sometimes.
Switzerland is a great place to tour though. We travelled all over by train and really enjoyed it. We travelled in December though - whole different issue weather wise but it's a beautiful country.