If you think the 7800GTX is going to drop to $150 before at least a year goes by, you're on crack.
Someone can toss that quote into their sig to check in June 2006 if they want to. If I'm wrong, I'm wrong. But I doubt I will be. The 7800GTX may drop to $500 if the R520 and a 7800 Ultra is released at $600, and then glide down from there to $400 a little after Christmas and $300 by this time next year, but nowhere near $150. I don't care how fast the R520 ends up being, there's no way nVidia could afford to sell this thing for $150 that soon. They'd absolutely BLEED cash and have no chance to recoup R&D. Will we see it drop to $500 before or soon after the R520 launch? Most likely. But that other $100 today is the price early adopters always pay.
You seem to be basing your pricing estimates on the R520 being twice as fast as the 7800GTX, or more. I'll believe that when I see it. I also don't even expect to see the R520 before October now. Why? All signs point to ATi having serious yield issues with that part at this time, and now that nVidia changed the rules with their 0-day availability launch, ATi can't get away with a paper launch at the end of July like they were planning to. Note they just forecasted their next quarter earnings will be another loss. This indicates they don't expect to see R520 volume in the channel next quarter, nor an entire R520 lineup to give them competitive parts in the midrange either (which is the real cash cow), which because of their earnings calendar means no significant next-generation volume before September at the earliest.