PLEASE NOTE: This is an opinion piece. You are free to agree or disagree with it. It is only here to give you an idea of how to value your radio.
For those of you that watch programs setting antique prices and want to trust PBS with the value of your radio, this article is not for you. I will also emphatically state that I am not an expert. Working with Grand Canyon Tube Radio, though, I have had to do a lot of research. I'm still doing much more. The thing I have found about any collectible, however, is that it's value depends on what people will pay for it. No more, no less. If you are talking about something that has been passed down from generation to generation in your family, the sentimental nature of it cannot be valued.
What is the value of my radio?
I don't know. There are many factors to consider. If you are considering buying a radio to resale for ten times more, my recommendation would be to consider buying coins or baseball cards. You might buy a radio for ten dollars, get it working and find someone to buy it for a thousand. Or you might find someone who will give you ten dollars.
The bottom line is the value is in the eye of the beholder. I, for example, like short wave. I want a console with broadcast (AM) and short wave and I want the little "police" label on it like the old RCA 94BT1. If you've got what I want, I have to pay your price. Except, of course, I can't afford $650.
Another consideration is as a family heir loom. Let's say your father who passed it to you kept it in the attic where the mice could get to it. You want to pass it to your children, but look at the condition. The wires are eaten through, two of the tubes are broken, the finish is peeling off and so on. You have to consider what you want your children to have. If you're into electronics, you can dive in and try to fix it yourself. Or you can get a qualified service technician.
Prices you find on web sites generally include the cost of acquiring the radio, parts and labor to get it restored, and a mark-up. Remember, web sites are generally businesses. They do not necessarily reflect the "value" of the radio.
What is a qualified service technician?
One step is to look to your local antique dealer. They may work with someone who repairs old radios. Of course, there's the Internet. You can check http://www.grandcanyontuberadio.com, for a start.
You might know someone who restored their old radio. Try them. They might do it out of love of the radio for the cost of parts. Of course, they might charge you an hourly rate, as well. If you find the former, try him!
What should I have done to it?
If you listen to those shows where they tell you that re-finishing a radio decreases its value, then don't have it done. The deterioration will continue until the legs start falling off of the console and you can see if someone will buy it from you. If you do decide to get it re-finished, it will most assuredly last longer, be a beautiful addition to your decor and be a great conversation piece.
What about replacing old capacitors and resistors with new? Will that decrease the value? Well, you might consider that very few people will walk into your house and say, "Well, that's a nice radio. Let's just pull it out and look in the back. Uh-oh!" Most people will come in and comment on how nice it looks or how good it sounds. Some old capacitors are even dangerous. Some contain PCBs which can cause health problems. Certain tubes are no longer available, but have solid state equivalents. While most technicians will not replace components unless absolutely necessary, on some instances, the "contamination" cannot be avoided.
If you turn it on and hear the rich, mellow sound of the tubes (which does sound much better than solid state today), then sit back, grab a book and enjoy.