Well... The cheepest Inno3D 320Mb Stock 8800GTS here in the UK is £185
an average-good 8600GTS here is £150... And the top 8600GTS is by know means as good as a cheep 8800GTS.
So waiting 2 weeks longer to salvage a bit more money is wiser then a 8600GTS, But by know means think that the 8600GTS is a bad investment.
The cheepest 8600GTS is dirt cheep at about £110 though .