Manufacturers websites will list all their models, some with price guidelines to allow you to go from least expensive to most. A lot of websites also have an " archive " feature which allows you to find information & brochures from past years.
Another source would be the NADA price guidelines for Motorhomes, which lists most models for each specific manufacturer.
2014 Newmar Ventana 4037 / 4018
2015 Jeep Grand Cherokee Ltd.
1940 Chevrolet Pickup