John,

The flares shown in the SAS Survival Guide are standard British Military issue. They are made by a company called Pains-Wessex. They produce a civilian version called the MIniflare 3. You will not be able to get people to ship these to you by mail generally, so you need a boat yard to visit. Some mountain shops sell them. They cost about £25 GB pounds. Try this website for details:
http://www.lifesupportintl.com/miniflare3SignalKit.htm
Several issues:
a. The flare doesn't burn long or fly very high (about 200 feet)
b. Relatively short shelf life, check out the expiry date before buying.
c. You'll generally only get red flares, although for the military there are white and green as well.
On a positive note:
a. they are reliable
b. easy to use
c. very compact

Hope this helps.