$300 is too much in my opinion.
Q6600 does perform slightly better than Phenom @ 2.6GHz. Check this benchmark
So, there is no doubt that Q6600 is overall better performer than Phenom 9850 at stock speeds.
Also, it seems that Phenom 9850 is a power-hungry CPU because it have high TDP and it doesn't overclock as good as Q6600
Q6600 is currently selling at $250 and it supposed to drop to $220 on April
AMD should sell Phenom 9850 for under $200 if it want to compete with intel