I am looking for Georgia maps for supported for Garmin device. Especially I'm interested in Svaneti and Kazbegi regions. Is there any place I could find such maps?
You can download Garmin Openstreetmap. In the drop-down list, just select Europe -> Georgia (they classifiy Georgia as Europe, even though it's mostly Asia).
Note that it does not cover topographic information, so it is not enough for hiking.
The Garmen GPS maps do not show detail in the regions such as Mtskheta where Kazbegi is located. I used and still use the free app maps.me in Mtskheta, Kakheti, Shida Kartli, Samtskhe-Javakheti, Imereti, Guria, and Adjara. To get this, you have to first download the app to your iPhone, then the Georgia specific map. It works offline, shows your location, maps directions, and has the pin points for some sites of interest.
Quite good maps you can download http://garmin.opentopomap.org/ If you want to get some GPS coordinates of Georgia Svaneti area, some trek coordinates for GPS device: http://www.zmidloch.com/outdoor-blog/svaneti-trek-georgian-caucasus/