Actually, they produced 6000 pairs -
https://www.head-fi.org/threads/akg-k702-65th-anniversary-edition.626971/page-180#post-9540313. That story of 3000 pairs was a mistake made by Hifiguy528
. Not sure whether it is an enormous quantity, but for comparison, Sennheiser has already made about 100,000 pairs of the Hd800, and AKG themselves has produced more than 20,000 pairs of the K812, and I remember even years ago the serial numbers of the AKG K701 exceeded 200,000. So, of course, the K702 AE is not as rare as the Audio-Technica L3000 (550 pairs) or Grado HP1000 (about 1000 pairs), but I guess it is as rare as possible with such an inexpensive headphone.
And by the way, they are not completely the same as the K712 and K7xx. If you compare the service manuals, you can see that the serial numbers of the drivers of the K712 and K702AE are different. And people wrote back then that the quality of the pads and plastic is worse in the K7xx. So, considering a unique color scheme and that the K702AE was one of the last headphones made in Austria before those people were fired by Harman (along with early pairs of the K812 and K712), I think it is a nice choice for an AKG fan, even if you have to pay a little extra for a pair.