2003 GSXR 750 Bike Value???
 

My nephew is selling his 03 GSXR 750. I'm just wondering if someone out there can give me an idea of what the value of this bike is. Details: Mileage 19,500, Runs and Drives straight, All plastics are broken including the tail. The Engine (Left Side) Plastic is the only one that's OK. The rear subframe is bent. It needs a valve adjustment and the Rear Brake pads need to be replaced. It has a Power Commander, Upgraded Exhaust Pipe, Steering Stabilizer, and Upgraded tires. Please help I would like to make him an offer but I don't know where to start.
Thanks