Do you have any proof of prices? I'm not saying that you are wrong, but I'd like to see some sort of evidence.
I've been around far too long to remember that whenever AMD had competitive chips, AMD's chips cost as much as (and sometimes far more than) Intel's chips. AMD is only lower in cost when they are not so competitive in performance.
AMD 1 GHZ Athlon released Mar 6, 2000 at $1299.
http://processortimeline.info/proc2000.htm
For comparison, Intel tried to save face with the 1 GHz Pentium III released Mar 8, 2000 at $999.
http://www.cpu-world.com/CPUs/Pentium-III/Intel-Pentium III 1000 - 80526PZ1000256 (BX80526PZ1000256).html
That wasn't the only time AMD charged more than your $650 level. In Sept 2003, the Sledgehammer was born with 64-bit processing and a $733 price tag. It stuck with the $733 price range for similar releases throughout 2004.
http://processortimeline.info/proc2003.htm
In 2005 the AMD 4800+ X2 monster came out. Price $1001.
http://www.anandtech.com/show/1676
And so on. AMD is often lower priced and often a good value. But AMD has a history of charging an arm and a leg (sometimes even more than Intel) when they have a great processor.