Jabby and Oz
You are being altruistic. Why should the normal VFR owner want his aircraft downtimed and stuffed around with to provide a surveillance system that offers him no benefits beyond the present? Answer, Airservices needs to provide some BENEFIT.
The benefit is NOT that of being able to operate in airspace as usual. If Airservices want to shift goal posts then forget the deal and let them keep the radar going. GA and particularly VFR stand to be more airspace restricted by ADS-B. Read the Airservices written NAS DP V1.4 about the Class E veils, and note the ADS-B Phase 2 mandatory ADS-B at CTAF R.
Therefore, Airservices needs to offer a sweetener. If Microair can include IN in the package, and that's a possibility, what a sweetener that would be. For VFR, if there can be a dashboard display display of the GPS data (admittedly the 145 display would not be to 146 standard) then that's a sweetener even if VFR pays for the display.
Creampuff
Ah so, that was a bit of fun, back to business. I doubt anyone in GA would accept the proposals without Airservices taking exactly the step you suggest and trotting out a list of TSO approved units and their cost. This is real caveat emptor stuff.
But it's also a circular argument until agreement in principle is reached as no manufacturer is going to gear up for an Australian mandate until there is some substance. We have seen the Airservices RFP withdrawn, Defence is perhaps an unwilling bride, and now Dick Smith is going to stop the deal - would you be investing money on that basis?
But, if we were to approach this as an unemotive business deal with Airservices the seller and everyone below FL180 a buyer, what would be the buyers specification and purchase motivation, that's the question.