Building on a corner lot in Brisbane

the answer to your question in fact is - "it depends".

I can share our experience with you, as we were/are in a similar situation.

We wanted to build a new house to fix all the mistakes we've made when building the current one. We've looked at the plans various builders offered, but didn't find anything we could fit our needs with just minor modifications. I ended up drawing a custom plan, and then we've picked a builder whose display house we liked the most (a medium sized builder). We've shown them the plan, they said "yeah that's great, it looks roughly similar to one of our designs, so we'll use that as a base for pricing". They gave us a base price for the house with standard inclusions for our custom floor plan, which as far as I can tell is on par in $/sqm with the reference design they've used, and then we've added all the really custom extras that don't affect the floor area/plan as additional inclusions.

We're still to start construction, so I can't tell you what the final outcome is, but so far the biggest pain point for us was that everything in inclusions was referenced as 'in lieu of standard', but for some items it was hard to figure out what the 'standard' is given it's a custom plan and we've upgraded almost every single thing from their standard inclusions. This is because their processes aren't really optimised for people building custom houses.

With custom builder you'd get a more personalised approach, but the price will also reflect that. We did check with custom builder when we realised that we're way over our original budget and are approaching the custom builder pricing with all the inclusions, but it ended up still being dearer.

Hope that helps. Also as a side note, I'd check if your plan will meet council requirements. I'm not sure whether having the garage and bedroom walls aligned like that is allowed, even if it is a corner lot. But I could be wrong.

well we didn't specifically look for one, it's more that the builder that was on top of our list of display houses we liked was happy to do it when we have asked them about it.

at the end of the day, if you're building on a small lot, all the houses are more or less the same, and there's not a lot of ways to slice that pie. you probably won't get much luck with volume builders, but medium size ones are more accommodating.

also while we're building a 'custom' house, we're not going via 'custom' process where you'd get architect to design it first, drafts people to draw up plan, someone else to come up with bill of materials and then you shopping around for builders to quote on it. we still went through their 'standard' process.