Geforce 4 Ti 4600 was a litte over $300
FX5800, 5900 were around $400
6800 ultras were theoretically $500 MSRP, but gouging was rampant because of the limited supply.
7800GTX is now $600, but with no gouging
This is not a pattern I'm very comfortable with, but considering a modern GPU is more complex than a modern CPU (maybe not in design, but certainly in production) and a graphics card includes RAM, a bunch of stuff for power managment, PCB, etc. I'm not at all surprised by the trend.
No ultra version until ATI has some competition ready. If you believe the rumors going around ATI is having a hell of a time getting all 32 pipelines working on the R520, I'm sure they'll figure it out soon enough, but until then I wouldn't expect to see an ultra version. I don't expect to see the 7800/x900 series show up in AGP at all, certainly not at a price point that makes any sense considering nforce4 motherboards are supposed to become very cheap. Personally I'm feeling very good about my purchase of a 6800GT about a year ago (flashed to ultra and then overclocked a bit past that to 425/1150). I'd much rather pick up an X2 to replace my 3500+ than a 7800 to replace my 6800, not that I could afford either one right now.