Hi Fourducks
Do it yourself - its fun and interesting and allow a year if you're not in a hurry.
I've subdivided twice in Perth and retained the original house both times. Also went Green title twice. One was cheaper than strata, as the sewer was right out the front and we didn't have to build a brick and tile carport and the other required a sewer extension for about $12k which was money well spent for a Green title block I think.
Its simply following a process. Submit plan to WAPC, get approval subject to conditions from WaterCorp, Western Power, Local Govt and WAPC. Satisfy conditions, get clearances and voila - you're ready for titles.
Here's what you can do:
1. get your lot details and head down the WaterCorp in Leederville, Find out sewer and water locations. If no sewer extension or under road drilling is required, green title won't cost too much more.
2. See your local govt. and ask what conditions they will attach (eg driveway width, retaining, fencing, existing structures.
3. Get a surveyor to draw up your plans and submit your application to the WAPlanning Commission on your behalf ($2k fees, but includes pegging and the deposited plan for lodgement of titles at the end which you have to do anyway)
4. Western Power is easy if you already have underground power. Pay them $1500 and tell them wher you want the dome.
Most of the above are consistent and straightforward in all their dealings with the exception of local govt. Document all conversations with them as their story often changes depending on who you speak to and what moood they're in.
Cost will vary from $10k for very cheap strata (ie no hassles) to $25k for a green title with some hiccups along the way. Don't be afraid of doing a sewer extension to get a green title - its just another step in the process and requires the engagement of a Consulting Engineer and your surveyor should also advise you through this.
Hope this helps
Mark