Welcome to the Stamp Community Family!
I don't know how much I can help with your questions, but let me give it a try.
First, the Postal Commemorative Society is one of those firms that typically attempt to sell overpriced goods to the non-collector population by placing ads in non-philatelic magazines and the like.
The stamps in question were a product of the Postal Commemorative Society back in 1983, I believe. They are genuine stamps, but are only a "partial set" of the lowest value denominations.
As has been reported on other websites, the quality of the stamps is fair at best, which greatly affects market value. The stamps are not particularly well centered (an important indicator of value in early issues) and there have been reports from those who actually removed the stamps from their sealed plastic capsules, that the stamps are often found to contain thins and other similar damage which diminishes resale value considerably.
As best as I can tell, the stamps used in the collection are "seconds" at best and the value of the stamps on the secondary market would only bring a small fraction of "catalog value", since the catalog generally values the stamps in VF condition. In fact, my 2011 Scott Specialized Catalog suggests that the values of the stamps in VG to F condition are only about 25% of the value of the stamps if they were in VF condition.
A nice enough collectible as it stands, but for those who seek out the best possible examples of these issues, money is often better spent in acquiring better quality material from other sources.
I did check a few
ebay listings for these Postal Commemorative Society Columbians and some are offered at a BIN price of $400 to $500, but with no indication that anyone has even bid on the items at those prices.