Danny,
When I was shopping for a Viper, I checked up to 10 sites daily. Most sellers advertise on multiple, but I didn't want to miss the car that might be posted to just one site. So, I checked Cars.com, Autotrader.com, Carfax.com, Cargurus.com, Carsforsale.com, ISeeCars.com, TrueCars.com...