Costs vary but for a standard community title subdivision appx $14k and for a standard torrens title subdivision appx $20k (this is through a company that arranges everything for a small fee, great value for money though and I really recommend it at least for the first time you subdivide).
The company I have helping me initially advised all up it should take appx 6 months, and I can see that without all the hurdles we have faced this would have not been a problem.
Maybe the company you are paying to help you should be offering some ideas...
But ultimately, no one is going to be as motivated to find an alternative solution as you. Try Dial Before You Dig to find location of various infrastructure.
www.1100.com.au Come up with some alternatives yourself - can you run the pipes via an easement through your existing house yard? Get some more details of what they have in mind, see if you can get someone to meet you onsite to have them step out what they are proposing.
We extended power lines (non-metropolitan) nearly 300m, trees in the way, etc. ETSA quoted 90K for the assets, plus unknown civil costs to underground it most of the way, plus easements as part of that would be on (our) private property - estimated to be at least 30K. After debating with the guy on the phone, I got him to come out and have another look. In the mean time armed myself with all the technical specifications for power line construction, boned up on the Native Vegetation Act, and had a number of arguments lined up...
When he came out, I got him to point out what they had in mind, then I said: "Any reason you can't keep it above ground, and put poles there, there, there, there and there?" (Five poles).
He thought about it for five seconds and said "Yeah, we can do that". Once I had him thinking along the right lines, he actually managed to remove the need for one pole by streching the spans out a bit. Net result? 75K total for the mains power extension rather than 120+.
Also spent about 45K extending water mains (in two tranches). Cost about $165 per metre (greenfields area, would be more if having to reinstate roadways, etc). Don't know exactly how much legwork they actually do for the quote, but the guy only came out with metre wheel and theodolyte in hand AFTER we had paid up. They ended up having to run it on the other side of the road to avoid some trees - guy doing the measuring/planning said they'd wear that...
I wouldn't be surprised if the initial quote was done based on mapwork rather than eyeballed...