I assume you want a wood boiler for under-floor heating? If so, I priced these a few years ago and the underfloor piping, manifold, etc. came to $20k and the boiler itself came to over $20k. So, combined, they would have been over $40k to install. That pretty much eliminated that option for me. Luckily, the property was in a Mediterranean/Temperate transition zone, so I went with an Earth-coupled
concrete slab, doubled the thickness of the external walls to fit in R4.0 insulation, and double-glazed all of the windows instead.
As far as I'm concerned, underfloor is only worth considering in Australia if you are in Temperate or Alpine region, and/or you can do the underfloor part yourself, and/or you can encourage a boiler to fall off the back of a truck.