If you want a decent graphics card based on Nvidia's latest Kepler GPU microarchitecture, you're going to have to spend at least $400 on a GeForce GTX 670. While it's true that the $99 GeForce GT 640 also features a Kepler-based GPU, that card is woefully underpowered and should really cost $60-70. The GeForce 600 series could have a new $300 model as early as next month, though. This story at Sweclockers claims the GeForce GTX 660 Ti is due to arrive in August.
Pictures of a purported GeForce GTX 660 leaked in May, so a late-summer arrival seems plausible. Adding a "Ti" moniker would only make sense, too. Nvidia reanimated its Titanium designation for last year's mid-range GeForce GTX 560 Ti.
The GeForce GTX 560 Ti started at $250, but the 660 version is expected to debut at $300. The higher price would put the new GeForce directly opposite the Radeon HD 7870 GHz Edition, which received an official price cut late last week. I wouldn't be surprised to see the new Titanium model arrive alongside a lower-priced GeForce GTX 660. The Radeon HD 7850 costs around $250, and Nvidia doesn't really have an answer for it.