advice on vintage tv buying

[Tube TV]

I need advice on how much is a fair price for a vintage tv ,I dont want to under bid or over pay . I want to add to my current collection and get a 1946 - 50 era televison with a screen around 7 " I would love to have a RCA Victor 621 ts but im dreaming . I would be happy with any make or model that could get . I am not worried about doing cabinet repairs and would love to do a full recap and other chassis service, and if it is working is not a issue . I don't really want to spend too much because im in BC , Canada and would have to ship a fair distance . which seems it cost around 75.00 ?
how high is a fair price in todays vintage tv market to pay for a set in this kind of shape ?
your comment please ,Murray