[Arran]

 The value is literally what someone would be willing to offer you, even though they are not common I don't think that they are exactly in high demand either, almost every radio-phono combo unit is like that. The first thing to know, and what any interested party should know, is that the radio chassis uses rubber covered wire with with the rubber tends to dry up and flake off with age. One common flaw that most 1939-42 Philcos also have is deteriorating plastic parts, this set is no exception, the pushbuttons are starting to crack, warp, and fall apart. Like any old radio the chassis will likely need to be overhauled, all old capacitors, filter and paper, and many of the resistors will need to be replaced, so because of this and the rubber covered wires it's not a good idea to power it up for the time being.
 The two main shortcomings of radio-phono combo units are the amount of space the cabinets occupy, and the cost of mechanically restoring the record changers, rotted rubber parts like shock mounts and idler wheels, some changers also have pot metal that can warp and self destruct.  Another drawback is that most of the combo units from the 1940s tend to look the same, regardless of brand, sort of a false credenza-sideboard look. So in terms of potential buyers you would be looking at a local buyer, or someone who could pick it up in person, and likely someone who is a Philco or a an old 78 record enthusiast.
Regards
Arran