Not what I've heard.
THEY DO need a TSO146 or WAAS position source in the U.S. for ADS-B out.
If you have an early (2004-2006) Cessna G1000 you're basically stuffed because it's TSO129. You have to buy the the Cessna WAAS upgrade, which I think is actually nearer $40K in Aus now. Then you need to change the GTX33 transponder to GTX33ES, which is another $4k or so. ($2000 for the exchange transponder and an engineering order and some labour.)
If you have a later Cessna G1000, you have TSO146 GPS and so all that's needed then is the GTX33ES transponder, which is basically slide in. But you still need an engineering order because it's an 'alteration' and Cessna have not approved it, so it will still cost you $4K... Oh, and you'll have to wait because you can't get the transponder due to 'high demand'.
Some folks say there are cheaper ways to do it by fitting a separate GPS source and Trig transponder or something.... But why would you have state of the art avionics and then cobble up something like that?
On the one hand you could say Cessna have let their customers down badly by not providing viable 1900ES ADS-B solutions, particularly for those with factory TSO129 GPS, on the other hand, why should they? They don't need it until 2020 in the U.S. and really it's a stupid pointless requirement for a 182 flying at 130kt below 10k anyway.