Price wise its seems to have gone through the roof snce Beatie was trying to get the private sector involved 12 years ago. Last I heard it was estimated around $150m in 2000 $. The scope has changed and now included a full dupliated line, alot of work at Petrie and I think adding some trackage on the main. The works at Petrie are more than significant and probably taking up a far chunk of the costs. Beatie's costing probably just had the branch connecting to the end of the siding on Platform 3.
I can tell you this will be one of the cheapest pieces of rail infrastructure built in Queensland and Australia in the last 10+years. The State was very lucky that there was a lot of infrastructure work on, and so was won with a very competitive price.
As for the actual price, and comparing it with numbers quoted 13 years ago, its a hard one to do without knowing all of the facts....
But
Did the 2000 estimate include the road works to get to the 6 stations? did it include 6 stations? did it include a grade separated junction at Petrie? did it include a new bridge over the North Pine River? did it include raising the Gympie Rd bridges? the cost of land resumptions etc and the list goes on....
As for any more greenfield additions, I tend to agree, but you could also throw in an extension of the Springfield line to Ripley if Ripley Valley takes off and the developers contribute to the extension.