The price of the ti4200 cards won't fall until ATI brings out their 9500 card.  The 9700 doesn't compete in the mid-end of the market, just the high-end.  If you were looking to buy a ti4600 it would be a different story.  I would expect them to start to really drop in price in about a week or so.  Also, if you're going to wait until the 9500 comes out (2 months or so), you might as well just get that instead.  It will be a crippled 9700, but from what I can read out of the specs it will still be able to beat a ti4600.