A number of companies regularly design, print, and sell commemorative illustrated envelopes or cards with hand-cancelled stamps postmarked with the date of issue (cachets, to a philatelist)¹.  A few companies have made available cards commemorating the issue of this set of American Scientist stamps.  Neither Feynman.com nor Friends of Tuva are associated with any of these companies and we don't endorse any of them, but we provide this information as a service for those who are interested.

• Fleetwood (http://www.unicover.com) sells a colorful set of the four stamps for $15.80 (all prices in US dollars) plus shipping and handling charges.  Contact them online or at 1-800-443-4225.
• Colorano sells a very nice set of four stamps for $12 plus shipping and handling charges.  Reach them at 1-800-533-2262 and ask about item 640-1929.
• Washington Press sells the set of four for $9 with no additional shipping and handling charge, and they will also sell individual stamps.  Reach them at 1-877-966-0001, ask about item number 3906-09.
• The USPS has an online site that sells blank white envelopes with the scientist stamps and a day of issue postmark.  However, for some reason I am unable to access this WWW site (using Mozilla as a browser) although I have been able to in the past.  Perhaps this is a temporary glitch and in the near future we'll be able to locate and report the URL for their page.