It's been out for a while, I have one and I am sure I have had it well over 5 years.
It was included in a 2 car set that included a '70 Pontiac Trans Am. It may have been sold in a different set also. But most of the ones I see for sale are loose like the one in that ebay auction, it seems rare to find a set in the original packaging.
There are also a couple Hot Wheel AAR cudas, and someone on another board said that HW is working on a new more accurate AAR, the ones they had before were inaccurate because they are shaker cudas with the race car paint scheme.
Maybe they'd reissue the Challenger too, that would be a cool set, to have the 77 Challenger and the 48 cuda.