It seems to me that, with a few flicks of an educated wrist, it should be possible for EBay  to profer an array of recent selling prices, shipping charges, feedback etc etc for an alphabetical list of cameras subdivided into model, year and condition : e.g. Rolleicord, Rolleiflex, leica, Nikon, Hasselblad, and let us not forget the  Spondo-Nurd  1883 Model   IVA  etc etc.