My first bike was a Yamaha 400. That lasted about a week. Next was a Kawasaki KZ650. Loved that bike. I've owned a few Magnas and even a VMax. Still miss the KZ650 the most.
KBB is a guide. NADA is what dealers use. Prices vary based on region but, condition, appeal, and popularity also have a lot to do with price. I don't mind paying a little more when the car was maintained well. The most important thing I've learned over the years is don't be emotional about...