BAL rating in Warralily and appropriate costs on a build

Hi everyone,
So it seems i'm stuck with a BAL rating of 12.5 (neighbour to my right has it,neighbour to my left hasn't).
Out of the quotes we have from various builders it amounts to aprox $3500-$4000 for a 26 square single story build...However,the builder we are likely going with have quoted a suspicious $5025....this is on top of flyscreens added as an optional extra.(they're stating that i'm only getting charged for upgrading them to a mesh)
When asked to provide a breakdown of the costs of the BAL they have simply stated that they go on per square of the house??....
It's annoying enough having this cost without it being beefed up by a volume builder......
any thoughts?
Mark

Our place is less than 25 squares, BAL 12.5 also. Our Charge was $5,150.
This included metal mesh flyscreens.

Seems about the going rate.

Our house is 22 squares, BAL 12.5 and we were charged $4,500. It includes aluminium mesh flyscreens to windows, but not the sliding doors.
We had a whole page of items that the BAL included, but not a price against each of those items.

wow that was quick!
Thanks,
Are you guys also in the Warralily estate or Armstrong area?
Mark

Nope, I'm in SA. In the Adelaide Hills.

I'm in Gippsland, Victoria

We are building a 31 square home, our BAL costs came to $4828 (flyscreens were standard). Our builder was able to provide a breakdown of each item included in the quote.

I just checked our contract, $5150 was for the stacker doors! Whoops... (the line above)

BAL stuff was $4510.