i think it may be too big for your specs, but i have been using the logitech m305 for a while and like it (plus it's only around $20-$25)

http://www.amazon.com/Logitech-M305-.../dp/B002Y6CJJ8

the best part about logitech's wireless mice is that the usb transmitter is TINY, which means i can leave it in all of the time and don't have to remove it when i put the laptop into my backpack