You can spend 300 USD, 180 USD, 90 USD or 70 for a night in a Double in Tbilisi- this amazing city does know its expenses. To do it cheaper becomes also more and more possible, as a lot of Backpackers and Students start to show interest in Georgia and the Caucasus.
Art Pension Murtazi: Nice breakfast and a really nice atmosphere for 25 .oo Euro. If you intend to stay longer than 4-5 nights you probably get a deal. In Saburtalo. (Prestige living area for Tbilisians, 15 minutes by car to the Old Town.)
Guesthouse Nika: With airconditioning and a firstclass service. 15.00 to 35.00 USD. In Saburtalo. (Prestige living area for Tbilisians, 15 minutes by car to the Old Town.)
High up in the Mountains in Tusheti, village Dartlo: Guesthouse Manana. Its senseless to describe the place, too beautiful. 25 USD incl. breakfast. For impressions visit http://tusheti.blogspot.com Contact me for details and bookings (up to 6-7 beds).
A bit more expensive (90-110 USD), but with a Jazz Bar in the basement and in the Old Town of Tbilisi: Hotel XX Century: http://www.20-century.com