It's absolutely legal here in the US to require businesses that sell your goods to not advertise prices lower than MSRP, if it is stated in some sort of 'dealer contract'. You could open your newspaper right now and find ads that have "CALL" or "Too Low to Publish Price" in the cost line. A pretty high percentage of companies have this practice here in the US, especially in the small boat industry.

That's not to say if you come down to your local dealer you won't get a deal on a boat. That's not the issue, it's the advertised pricing requirements that are the problem. Aussie laws are different than here.
I sell both Aussie boats and US boats and have read a lot about the different trade laws.