Never seen these that cheap. Usually around £100
Experience incredible responsiveness with the G703 wireless mouse using Logitech Lightspeed technology
Near instant mouse actions whether you go wired or wireless, up to 8x faster reaction times over standard mice
Extremely accurate PMW3366 sensor, used by gaming enthusiasts is capable of up to 12000 DPI sensitivity
Experience incredible responsiveness with the G703 wireless mouse using Logitech Lightspeed technology
Near instant mouse actions whether you go wired or wireless, up to 8x faster reaction times over standard mice
Extremely accurate PMW3366 sensor, used by gaming enthusiasts is capable of up to 12000 DPI sensitivity
Heat!
Heat.
I think the main difference between g603 and g703 is that g703 doesn't require batteries and can be charged via USB, when g603 works on batteries. Also g703 has a slightly better sensor, if I'm not mistaken. And one last thing that I don't find important at all is RGB lights