I live around your area, and do renno's for profit on places similar to what your asking.
50k is very skinny depending on what finish you are after and what materials you are dealing with and whether you are doing the work.
3 bathrooms:
Removing all tiles, but replacing them with what? Floor to celing? tiled shower bases etc? Work off $100 a square meter at a minimum for just the tiles, that will include removing them, getting a basic "OK" looking tile, and having it laid. I'd be allowing at least $500 per shower base, that will keep you safe depending on what you go with, a little room for a poly marble, and probably bang on what having it screeded and tiled will cost.
Then we come to baths: freestanding will be cheaper than a hob, for obvious reasons. Allow $1000 minimum.
Plumbing: pretty much count every point in the bathroom, multiply it by $150 and you should get an idea. Taps count as points, waste points count etc.
Does it have a toilet in the bathroom?
Fittings:Obviously this varies, but you will struggle to get a decent vanity and basin/s for under $400, taps, shower heads, they all add up.
I think you should work off about $4k as an absolute minimum if you are gutting the bathroom of everything besides the plaster, and thats assuming the walls are perfect and need no alterations, and you dont have to move any plumbing etc.
The kitchen: If you are getting it custom made, basic PVC or laminex, standard size with a breakfast bar etc, work off about $10-12k plus appliances for a medium finish, that will look like an excellent kitchen for your average joe. (This is not including bench tops)
IF you want stone, you are looking at another $3k+ for most standard kitchen sizes.
Floors: Solid timber? Polished?
For a polished timber floor, work off around $90 sq/m as an absolute minimum + $laying. For 4 bedrooms, a kitchen and living area, you are looking at probably close to 7+ days of man power to lay a standard house with that many rooms, work off $80/hr if you can find the right carpenter with an apprentice etc.
Painters charge a fortune, I'd be looking at doing it yourself, for a 4br house in our area, you are up for easily a couple of grand in retail paint costs, and thats if you have all the paint gear you need......
As you can see, none of this includes internal fittings, i.e door handles etc, lights, sparkies, plasterers if need be.
Basically I don't think $50k is anywhere near feasible on a 4br home with 3 bathrooms and a kitchen..........Or your medium finish is alot lower than mine.......
For instance, I will be putting some pictures up soon of my PPOR im flipping at the moment, it's about to go to market. It was a 3br, I extended it adding an open plan and an ensuite, making it a 4/2/2, not entirely comparable because of the extension and it was completely re-roofed, but I also got a heap of materials for nothing, 90% of the labor was free and had 1 less bathroom, so it may even out, but that was around $100k, to what I'd consider a medium-high standard.
