My experience from Batumi 2.5 years ago: There will be several guys contacting you in grindr with offers for paid sex. Rate should be around 50 USD for young next-door type guys; maybe slightly more because Tbilisi. Expect to negotiate. If you are looking for gym fit, muscle, models it will be more obviously (if available at all). You can try Hunqz also; expect to pay more than Grindr guys.
Let us know how it turns out.