Doha is the main city in Qatar and can be synonymous the whole country.There are other small towns you can discount 10%-20% from what you will be spending in Doha.
Doha:
Rent:a decent two b/r apartment costs somewhere b/n 7000-8500 Qatari Riyals

Food is cheap and you will be spending on average somewhere b/n 1000-2000 QR depending on your lifestyle

Transport is a big problem.Till the time you arrange for the license you will spend around 1000-1500 QR on transport.

If you have any other questions,just shoot them.