There was a sale going on up here in canada (toronto). A BFG 7600 GT OC for 175$ - 50$ mail in rebate... Although the rebates take a while it was quite the outstanding price. You cant go wrong for a 125$ video card like the GT (after savings). I would be reluctant to purchase a 7600 gt for more then 200$ though.
They are both good cards its a hard choice. Ultimately though the cheaper card that provides the same bang, is worth the route to go. You cant go wrong with a BFG either specially for gaming.
Also no reason to wait for DX 10. They wont be making any games any time soon that aren't backwards compliant with dx 9 cards. Think about how many people out there upgrade recently or in the past. Game publishers cant catter to only DX 10 people. The 7600 will last you until the summer of next year and youll be able to play the latest games.
Granted you cant play with the highest resolutions and details possible, but then again you cant really do that with most cards under 250$. Its a tough call. Waiting only makes the old cards cheaper, and the new ones more expensive. So unless you think youll be dropping 500 to 600$ in early Janurary when the r600 from ATI comes out, theres no point to wait it out. Otherwise you can wait forever because its a fact next month will yield better cards and prices.