My builder ONLY does raft slab, but my quote on base price is very competitive with the volume builders who where only offering waffle pod. I'm actually happy about the raft slab, I trust it more.. even though my site is very flat, non-reactive.. well so I expect given all builders quoted me fixed costs of 5-10k. Haven't gotten to soil report stage yet.
Hope you can find a better builder to bring those site costs down My builder is a smaller local builder (they do more custom mansions, although they are building me a tiny little 3bdr), located in Melbourne. I would be happy to PM you the name, I think they do mostly/only the east and south eastern suburbs, but you never know.
I'm also glad that we did a raft slab. My understanding is that there have been lots of issues with slab heave in waffle slabs and M was even sued and had to rebuild a house due to a defective waffle pod slab.