Note that many G303s have a sensor-rattle issue (https://www.youtube.com/watch?v=lI6UulAMWnQ).
I bought my G303 from Best Buy a couple months ago at $40, brand new, had the sensor-rattle. I went through Logitech's RMA process and got a new G303 without sensor-rattle; I did not have to return my other G303 (YMMV).
If you decide to get the G303, make sure you test for sensor-rattle and try the RMA if it happens on your purchase. I tried to return the defective G303 to Best Buy, but I missed the 15-day return period; the RMA process took about two weeks total, so there wasn't much I could do without the 30-day return period from Best Buy Reward Zone membership.
On a side note, I didn't notice any effect on gameplay due to sensor-rattle; both my G303s function pretty much the same, and the rattle is fairly difficult to hear without a silent room. I'll keep it as a backup, maybe try to fix it manually, or give it away if it comes to that.