Whatever you do, don't go to Eden Brae. We regrettably have signed with them and are way down the path.
their standard range has very limited choices and these choices are often too basic. Everytime you deviate from the standard range, it is a chance for them to charge more, even though the cost of your preferred choice is probably the same as the standard. This is their business model and this is how they make their margin.
Don't get fooled by the supposedly good value 'upgrade package' either. You will realise later you need to spend more to make the upgrade worthwhile. One example is the 'free' or 'low cost' ceiling height upgrade, the sales people will never tell you it will only look good if you have correspondingly higher doors. You want higher doors? We did and spent a further $5000. You wouldn't think adding a few centimetres to the door height will be so expensive but that's how they get you. I later figured out that few extra centimetres cost a few times more than a whole new door you can get from Bunnings from the same brand.
The tender will cost about a few hundred ($700 from memory) and it will cost a further $2000+ to draw up a contract. It is not an insignificant investment so you want to do your research before you enage in a tender or two. Also if you are getting more than one tender done, make sure you have a list of things for them to quote on, so you are comparing the same things.
You want to upgrade things that are hard or impossible to do later, things like insulation, lighting for downstairs (if you are building double storey), staircase, kitchen, windows and doors. Things you can leave for later would be joinery, perhaps floors.
Upgrades are where they make their most margin. There are two layers of margin here - one for the suppliers, and the suppliers will also pay Eden brae a commission.
One thing that makes me very uncomfortable is they never give you an itemised quote even if you request it. And they don't allow you the opportunity to get the items quoted before you sign the contract. So you really go in blind with just some faith in good business ethics. And your faith is not always rewarded.
And how is this any different to any other project builder? They are all somewhat the same I'm afraid. If you want luxury and personalised Spec double the budget and get an architect and private builder.