In general yes the flat prices outside of zurich are cheaper.
If you stay away from the east side of the lake that is.
(Duebendorf will give you more for your money than Zurich)
Tax is cheaper outside of zurich and this means that rents tend to be a little higher than they should be.
tax calculator
Use that and stick in some post codes off of homegate to get an idea of what the tax differences are.
I guess it goes like this, out of zurich you are likely to get more for your money and you will pay less tax, however the rent will be bumped in certain areas to reflect this. Its up to you if the tax benefits and extra space, outweigh the travel time and the rent.
Personally I like to be out in the country side a bit more, if you like the city life then you have to pay the premium.