If you're on a really tight budget, here is a mouse you might consider. I actually bought one of these as a backup for my SteelSeries Ikari on a whim. I have to say I'm pretty happy with it considering the very low price.
It has 3 switchable DPI (500, 1000, 2000). It's not variable dpi, but that's not really something you see in mouses this cheap anyway. Also has a couple of side buttons (which is a requirement for my tastes in any gaming mouse).
The rubberized buttons are also quite comfy and feel great. The only thing I don't really go for is its obvious design preference for a claw grip. If you like a mouse to fill the underside of your hand (palm gripping), than it's probably not the best choice.
The lift-off distance is also pretty high, which I've heard can be adjusted with their various firmware versions (I haven't tried). At any rate...worth a look and yet another low-cost alternative for a gaming mouse.
http://www.newegg.com/Product/Product.aspx?Item=N82E16826570014