The link leads one to conclude that there could be roughly a half million different stamps.
There are thousands and thousands of different postage stamps. The US has issued over 4,700 stamps without counting airmails and revenues.
Without knowing what stamps you are refering to, it is impossible to offer a value. Stamps are issued from virtually every country in the world, as well each country issues many different stamps each year.
22 stamps
That would depend on where in the world you were posting from and what denomination of stamps you were using.
Beyond counting
19 ways
356891011121314151617181921222427total 22 different amounts of postage
Hundreds of stamps are issued each year around the world. Each country will issue different stamps throughout the year.
As the name implies, it would have eight stamps. It can be 4 by 2 or 2 by 4, usually depending on the stamps, particularly if there are four different designs on the same sheet.
There have been over 4,500 insect stamps issued throughout the world. These stamps show over 1,800 types of insects and are collectible.
They are called catalogs. There are a number of them available from many different companies. In the English speaking world the Scott's Postage Stamp Catalog and the Stanley Gibbons are the most common. They can help you classify and identify stamps and provide a rough value.
One penny for the first in the world, in England. The first stamps in the US sold for 5 cents or 10 cents ( There were two different stamps offered.)
That it was stamped six times. The significance of the stamps themselves depends on what the stamps are.