Not mid 20's. But maybe $18-19k. The fact that you judge the exterior to be a 7/10 could cause slight drop in value. Fix the paint chips and detail it well. Last year I paid $19.5 for mine with 45k miles, single owner, and showroom clean. Looked and smelled like new. I paid higher than most people but I don't care. I haven't seen a listing as clean with the same mileage for a better price since. Ask a little higher than what you want because everyone wants to beat up the price to feel like they got a better deal.
2009 G8 GT, White Hot, Cortex, Camaro Trans Pan, VCM Intake, GXP Mufflers