Bill Zuber was a professional baseball pitcher - just in case any other Blurtit members were wondering who he was - and I suspect that this is the type of postcard you want to find a value for:
It's hard to be precise about the value of your Bill Zuber postcard, as I am by no means an expert, but the first thing I did was to check how much similar cards were selling for on various auction sites.
I found an autographed Bill Zuber postcard on Proxibid, which had sold for $4.25 - and you can read the details of that listing here.
I also checked out eBay, and this was the most up-to-date series of listings I came across, here.
You'll see that someone on eBay is trying to sell a card which looks identical to the one on the Proxibid site for $21.00 on a Buy-It-Now, but I'm not sure that this tells you what the card is really worth.
Your best bet might be to get hold of a copy of The Standard catalog of Vintage Baseball Cards, either by buying one from Amazon, or perhaps by borrowing one from your local library?
This might give you the best advice on what the value of your Bill Zuber signed postcard really is. Good luck!
