There are a couple dozen of them. Once place to look would by the Mystic stamp catalog, available online. Or a copy of Scott's catalog, usually available in your local library.
Yes it will be delivered. That would be enough postage for two ounces at today's rates. US Postage stamps haven't been devalued in over 100 years.
20 in a book, 100 in a roll (assuming you are not talking about a collectors book of stamps).
First of all you have to be sure it is 'rare.' There are hundreds of six cent stamps that have been issued, some well over 100 years old. They could be worth anything from 6 cents for postage if unused to hundreds of thousands of dollars. The first US 6 cent stamp #115 was issued in 1869 and the mint version can be purchased for $1,750. There is a 1909 #362 that is worth $18,000 if used on envelope.
You can buy discount postage stamps at warehouse prices from companies such as CostCo. You can also buy them through stamp dealers such as hgitner.com. The stamps must be purchase in large quantanties of at least $100 worth. The USPS offers discounted postage rate. This can be purchased online and you must print them out with your printer.
Copies of the book are selling for about $80-$100 US.
Unlike some countries, the US has not devalued postage for over 100 years. The stamps are still valid for their face value. You still need 44 cents to mail a first class letter, but you can get that with any combination of stamps.
The Queen Victoria orange half penny stamp is worth around $17 if used, and $100 if unused. Some varieties can go as high as $1,000 if unused.
Laotian currency changed in 1955 - 100 cents = 1 Kip
It is in various rates, stamps will cost either a few cents to a few dollars. about 42 cents a post stamp
Some are 1 cent and some are 2 cents It depends on the stamp. Most countries have postage stamps that range in value.
There have been 6 cent postage stamps available almost since there were first postage stamps. Assuming you meant to ask "When did it cost 6 cents to mail a letter?" the answer is: In the U.S. from 7 January 1968 through 15 May 1971.
SC represents Scott Catalog to the philatelic community. The Scott Company has been documenting and printing catalogs for almost 100 years. Other companies would include Minkus and Stanley Gibbons.