There are some relatively new stamps that are fairly scarce. Some are valuable, others go for next to nothing. Why the difference? My theory is it comes down to the basic tenets of economics. Supply and demand. While most of these scarce issues have a low supply, the demand is just not enough to drive up the value of the stamps.
One example of this is the stamp shown here. This stamp shown here was one drawn by someone who attended the Telabul stamp show in May 2004 in Tel Aviv. A few months later, the postal service issued a similar stamp with a different drawing in the center. Examples of the stamp with different drawings in the center are fairly scarce, as I believe the only way to get the stamps was at the show, and each design was limited to 2 sheets, and each sheet had only 3 tabs. In theory, there are only 5 other tabs that look like the one example I have. When I bought the stamp, I was told that there were only 10,000 sheets printed total, which would imply 5,000 different designs, and 30,000 tabs. So, if demand were the same for this issue as it is for the early issues of Israel tabs, this stamp should have the same value as the early tabs. But the demand is just not the same. Why? One reason is the album makers do not have a place in the album for this variety. It does get mention in the 2006 edition of the Bale Catalog (1587a/b, IRS 71), but it is not mentioned in the more mainstream Scott catalog. If it had a spot in a standard album, I believe demand would go up. No one likes a blank space in an album, but it is easy to ignore, or to not even be aware of stamps that have no spots in the album.