The cost of an ILS is approx 6million (includes the cost of upgrading approach, runway lighting, flight inspection etc). The ongoing maintenance is approx 1million/year.
Neddy, the Albany Council put one in for a couple of Fokker flights a day: I don't think they'd do that if they cost $6m and $1m maintenance a year...
Get with it guys: Non-Precision Approaches SUCK! The graveyards of the world are littered with the bodies of people who were in the back of big jets trying to do NPAs. It WILL happen, and for a place like YBCG, if the use of NPAs is as much as stated here, they should have an ILS.
And when it does go in (the ILS that is), for god's sake put a DME at the end of the runway, unlike the morons who put in the CS 33 LLZ and didn't bother putting in a DME to go with it on the threshold. The most complex NPA in Oz for big jets and they left the only DME 3 miles up the other end. What hope have we got!