Wilson produced this model in 1973. Unfortunately, it isn't a highly sought after glove.
The first strike against it is that it probably is an "imported" glove, made overseas rather than in the USA. Collectors tend to go for the made-in-the-USA gloves. The country of origin should be stamped somewhere on the glove. It might be a USA model, as this was the era when Wilson still made some of their gloves in America, but even if it is it wouldn't affect the value very much.
Gloves from the 1970's are not very rare, as they were mass produced in the millions. And, while Blair was a fine player, he wasn't a Hall of Fame caliber popular player. Gloves bearing the endorsement of popular Hall of Famers are the most collectible.
Lastly, this particular model was a small, inexpensively made kid-sized glove. To give you an idea of what that means, in 1973 Wilson sold perhaps a dozen different models of fielders gloves. The top-of-the-line A2000's retailed for about $50. The A2620 was the least expensive glove they sold and it was about 1/4 the price, around $10. The price difference illustrates the difference in size, workmanship and quality of materials used on the least expensive gloves. Collectors tend to look for full adult-sized, top-of-the-line models.
All that works against this being a highly collectible glove. Even in mint condition, there just isn't much collector demand for this particular model. I would put a top retail price on it of maybe $25-$30...if you happened to find an old Baltimore Orioles fan who followed Paul Blair back in the day.
Hope that helps!
Bret @The Glove Shop