Thanks to one of our anonymous commenters for bringing this to my attention. Circuit City and Best Buy finally have some AGP versions of the Radeon HD series available. I also looked at Newegg, CompUSA, Fry's, ZipzoomFly and TigerDirect but I found nothing at any of those retailers. Here is what I found:
The VisionTek HD 2600 Pro at Circuit City and Best Buy are identified by the same model number (A2600P256AGP) but Circuit City says the card has GDDR4 memory and Best Buy says it has DDR2 memory. The box pictures on both of the sites show that the card has DDR2 memory.