I haven't really been a wholehearted embracer of the various Burger King cards Topps was rolling off the presses in the late 70's, probably for the same reason I don't really take to the mid 70's Hostess cards (a Topps production photo-wise)-they just seem like separate food issues. There is a story worth telling though concerning the most valuable of the Topps produced Burger King cards-#23 in the 1977 Yankees set, namely one Lou Piniella.
I looked on Ebay for a scan, that was the only one for sale.
I'll get into the vagaries of the different BK sets eventually (maybe) but the '77 Piniella appears in the first set Topps produced for the home of the Whopper. The BK cards resemble the regular issue Topps cards for the five years they were issued but sometimes baffle novice collectors since many of the specialty cards have the same fronts and backs as the normal Topps cards but with their own numbering, usually from 1-22. The '77 Yankees set was intended to have 22 cards but it took the intervention of George Steinbrenner to have a card of ol' loudmouth Lou included.
To hear Sy Berger tell it, in an articleI found online at Google Books (from an old edition of Inside Sports magazine), the scuttlebutt in Spring Training was that Piniella was going to be traded and Sy made the executive decision to leave him out of the set. To quote the article Berger stated Piniella got off to a hot start and "George Steinbrenner called me up and said there was no way we could distribute Yankee cards without Piniella." It must have been a heated discussion as the article notes Berger winced when recounting it.
The Piniella card sells for a multiple of about 100 times what a common goes for and does seem to be in short supply. Not scarce but perhaps a hoarded card.
There is some more here, on the Gothamist that is well worth reading (as is Gothamist generally).