That's a great Penguins Pennant. Do you know for sure that it was sold at the stadium? Perhaps it was sold only via the Catalog, and that explains the rarity.
I'm guessing 98% of all pennants were to sold to fans in person/at the stadium, as opposed to them mailing in. I worked for a major (top 10) Food Company, who did Mail-in discount coupons as well as IRCs (instantly redeemable in-store coupons). Redemption rates on the IRCs were in the 90% range, as opposed to roughly 2-3% redemption for the mail-in type.
Most people just don't make the effort to complete paperwork and mail-in, and seem to prefer the ease of an impulse-driven purchase.
Just a theory... However, if you know for a fact that this pennant was sold at souvenir stands within the stadium, then
nevermind 