Welcome to Stamp Collecting Forum.
In response to your question about the Ohio Prepaid Sales Tax Stamps, they are an interesting collectible, but unfortunately there's not much value to them to collectors.
In fact, here's a link to 47 listings on Ebay where these items are being offered for sale, and even with the prices listed, no bids on any of the material has been placed:
http://www.ebay.com/sch/i.html?_fro...l-CategoriesIt's something like the War Ration Stamps of World War II. They, too, are interesting to collect, but because of the millions of them in circulation, the resale value on them is next to nothing unless a collector is looking for a very specific item.
A simple cliche we may use on SCF is "old" doesn't necessarily mean "valuable". There are stamps from 100+ years ago that are worth barely a penny or two on the secondary market, while others are worth a small fortune.