Aqara Window Door Sensor - MILK WHITE $4.99 (~ A$ 9.76) - https://www.gearbest.com/access-control/pp_626703.html
Price: US$ 4.99
Coupon Code: AU16randSE
Limited to first 50 stock,1 times per account,AU,NZ,MY,SG,BD,LK only
P.S: This is supposedly the newer version but I don't what the differences are between this and the "Original" version.
Original Xiaomi Smart Door and Windows Sensor - SMART DOOR AND WINDOWS SENSOR WHITE - https://www.gearbest.com/smart-light-bulb/pp_257677.html
Coupon Code: AU16randSE1
Limited to first 100 stock,1 times per account,AU,NZ,MY,SG,BD,LK only