Life in Erbil can be expensive, You will not find fresh milk here, it is all in a tetrapak starting at about $2USD per liter. Yogurt is available here and relatively cheap. You can find channa dal, masoor dal, brown lentils, rajma, and some other beans here. Dried beans run about $3USD per kilo some a little less and some a little more. You can buy chapatti atta at Majidi Mall in the hypermarket. They don't always have it and it is sold in a huge bag. Rice is easily available here too and not too expensive.
I spend about $100 a week on groceries for myself only. This is eggs, bread, veg, fruit, rice, etc. But it can be done for as little as $50 per week if one is careful.
Transport can be expensive in taxis, Cars are cheap to buy as are motorbikes but there is no insurance here which means if you have an accident you pay.
On $3000 per month if your housing, electricity, and other bills are paid you could most likely save $2000 a month if you are careful.
Flying in and out is very expensive but get on the mailing list for Etihad, Qatar, and Emirates because they do have fare sales. I got a return ticket from here to Delhi for only $535 by buying in advance. Otherwise they run around $800 or more.