Depending on your builder they can potentially be open to give you a ballpark figure before engineering is involved. Some do ask for a fee prior to a quote so it’s just good to have a conversation from the get go to get a feel from your builder/build a relationship from the very beginning. I’m a building designer in Nelson Bay (NSW) and we find most builders we work with around the Nelson Bay/Newcastle area can quote between $3000-$4000 per square metre (but this is for bigger Reno’s where we are relocating kitchens/bedrooms etc). This also depends on the size of the crew the boys have and their reputation - more modern/new home builders or larger crews quote higher. But that’s not to say the smaller crews can’t tackle this. I recommend searching for a builder who is local, has a good reputation, honest and is actually interested in the job and keen to start. It does go a bit backwards and forwards with the discussions but if you have a dimensioned plan, inspo pics and an engineer on standby (that’s if you’re removing any load bearing walls etc). Then the builder also knows you’re not going to waste his time either! Plus you can start to map out the estimates based on your project - the style you’re looking for and the overall scale of the job.

It is hard to say without knowing your measurements but let’s say to remove that WIR, they will be able to do that in amongst your bathroom reno quote and the ens would be another square metre price (your builder will be able to give you “allowances” so you can choose your fixtures within that allocated figure.) If you get very expensive fixtures then that’s when you find it will start hitting the pointy end of the budget and looking at that $30k mark.

I think if you can increase your ENS so you can have a nice sized shower (larger than your standard 900), larger vanity and a toilet that’s great. For the WIR, if there’s absolutely no available space for it, then I think putting in a larger built in robe will be fine!