Tbilisi and Batumi are the most expensive for rent but still surprisingly affordable compared to western cities equivalent in size. It depends on your standards and the value of your native currency. If you're earning Euro, GBP or USD, it's surprisingly cheap to live here. Once you get sucked into the GEL economy (being paid in lari), it's probably time to move.
As far as buying property, homes, condos, you can spend as much as you would in any western city, pending on preference.
You can find a two bedroom flat with modern comforts in a scenic (enough) area of Tbilisi for as cheap as 350 USD (the unofficial currency of trade in Georgia). One bedrooms go as low as 200 USD. You can find even cheaper if you're willing accept less than modern accommodations in a less than ideal area.
Always ask a Georgian native speaker to negotiate - as everything here is negotiable. Upon hearing even the slightest foreign accent, the renter (or vendor of any product) will increase the price instantly.
Depending on where you are from, eating (in general) can be difficult here once the initial exotic flair of the local food has worn off. The better quality food you require, the more expensive it will be. This is applicable to both shopping in "super" markets and in restaurants. Unlike western countries (USA especially), cooking at home is roughly the same cost as eating out - unless your palate favors Georgian cuisine in which case you can eat in/out for almost free.
If you must drive, petrol is slightly cheaper here but not enough to warrant the stress incurred by doing so. Public transportation is one of highlights of living in Georgia. This is true in the cities as well as rural areas. Taxi, buses and marshrutkas (minivans) are available from one end of Georgia to the other for unbelievably cheap fare,
Georgia is one of the cheapest places to live. Just come with your own currency.
