It's probably an "amnesty" sale like the one I upgraded to P4 with. It was a sale so that people who had bootleg versions of the software, or an older version from one of the magazine discs (like I did) can get a full legal version of the program. IIRC there was quite a to-do over it since it allowed people who had pirate copies to get the program cheaper than people who had bought a legit copy when it was released.