This tracker is a couple of years old now but the cheapest I have seen it.
It is also on sale at a number of other retailers below but not as cheap as this (which also includes delivery)
Usually $219.99 at Life Pharmacy
Link for Storm Blue(lifepharmacy.co.nz) - also $153.99
Price elsewhere:
Harvey Norman:(harveynorman.co.nz) - $188
JB-Hi Fi(jbhifi.co.nz) - $168
Noel Leeming(noelleeming.co.nz) - $189.95
Pb Tech(pbtech.co.nz) - $168.99