I don't know for sure if they will have this particular Go-pro but there is a shop in MBK, IIRC it's on the same floor as most of the other camera shops, not the floor with all the mobile phone kiosks.
It is toward the National stadium end and in one of the centre cross overs with the entrance facing away from National stadium. It has several large display cabinets and a wide entry.
I purchased a Go-pro chest strap from them but did note at the time that the camera prices were more than I could purchase them in Aus, but that goes for most tech gear.
