Here @ tpf, in the price checks forum, if you link the thread from here filmys will find it and take a look.
Its the only way to not fall foul of the rules..
The problem with many of the older cameras is that the desirability of a camera depends a lot on small differences.. the exact model, combination of shutter and lens (which may have varied over the course of manufacture or came in standard/premium combinations for the same model name/number).
As an example, you've listed Kodak Retina and you'll find the going rate for a clean working model varies between less-then-£30 and £200-plus depending which model, etc.
Camerapedia is pretty good for getting the identification in most cases and provides useful links. Ebay completed listings will give a good idea what people are prepared to pay.
Is the valuation for probate (you mention he was left them) or for sale?