[Arran]

I guess we would have to see the cabinet to figure out whether you should have kept walking. Is it complete? As in are all of the knobs and the speaker still with it? How about the grill cloth? I know that people try to appraise based on the value of the tubes but remember that these are used tubes, even if they all test good it isn't the same as if they were NOS and still in the original boxes.
I always take the view that the main cost of a radio is usually not in buying it, it's in restoring it, quite often you can end up further ahead by buying another example of the same set in better shape for a few dollars more.
That being said $10 was probably all right as long as the cabinet isn't an absolute wreck. The circuit is fairly average, really just a 1938 version of a AC powered AA5 with an eye tube. I found a picture of a similar set over on the radio attic site and it doesn't look too bad, it reminds me of a "Plant A"/Clinton set.
Regards
Arran