Really waiting for native usb 3 webcams to hit the market, atm the life cam studio is probably about the best for planetary on a budget. The old 900nc still pulls it wait though and if you get into modding you can do some great things with the old girl. You could try sharpcap and see if you can change exposure and gain with it, though with a min of 10 Lux it really sucks
gary honis has some guides on modding the fusion and life cam studio on his site and the results and the life cam kicks some butt on a budget.