Cheapest I've ever seen.
($53 via Officeworks 5% Price Guarantee according to josh12341.
Logitech G502 Proteus Spectrum RGB Tunable Gaming Mouse with free shipping for AUD53.90 + Custom Duties = AUD 56.17
(Model 910-004615)
Accurate responsive optical sensor
Balance and weight at your control
Programmable RGB lighting
Personally-tuned performance
11 Programmable buttons
DPI Shift In-game
Dual-mode, Gaming-grade Scroll Wheel
That's pretty good. They don't hold up well over time, but really good mouse. Bought (core) for $69 almost 4 years ago, it's shedding rubber around the thumb grip and I don't really use it much.