Can confirm, my heat pump died a few weeks back, I contacted one of these, was quoted $6500 to replace my unit. Looked up the new unit saw the good guys selling it for $1650 so more than $4k for the install/replacement.
While the guy was onsite doing the inspection i made a comment that my original install cost $500-$800, his immediate reaction was, “we may not be the company for you”.

Bunnings managed to replace it with their installer network for $2900 all done and a better unit than quoted by these sharks. Really happy with the installer, was a local guy anyhow, seemed very professional and took a careful approach. Even told me about a few steps that others may skip. Job took 2.5 hrs.