Will Q9550 price drop soon?

doubtful, the socket 775 CPUs are getting rare and finding upgrades are harder and harder which often results in high prices.

look at the high prices for athlon x2 CPUs

Nope. Price will only go higher as it becomes rarer.

BUT price could go down if people stop buying them. deals maybe?

you may have to wait a while for that...like another two years

I bought my q9550 a year and a half ago and the price has actually risen since then (239-260USD).

Core2Quad prices have been slowly climbing since I3/I5 released last year, and more models are becoming hard to find. I wouldn't expect them to drop.

As already mentioned look at the old socket 939 Athlon X2 processors, they sell used for more than a new Athlon II X4 costs.