Australia is yet to formally decide on the total purchase of F-35 Joint Strike Fighters (JSF) from the US, but the director of the Pentagon's F35 program says the planes are getting cheaper over time.

Lieutenant General Chris Bogdan says he is confident that by 2019 each of the stealth fighter bombers could be delivered for between $US80 million and $US85 million.

The first two of Australia's initial order of 14 F-35s are expected to be delivered this year at a cost of just under $US130 million each.

Federal Cabinet's national security committee is expected to endorse the next tranche of JSF orders when it meets next month.

That should bring the total on order by Australia to 72 planes.

The Chief of Air Force, Geoff Brown, says he is still hoping the eventual number of RAAF operated F-35s will reach 100.

"I think our options are open but Air Force's ambition is still 100 JSFs eventually. I think over time it will depend on what the world looks like," he said.

Whether it is 72 or more planes, the reduction in price will represent a huge saving to acquisition budget, but for Australia the F-35 could also prove to be a money spinner.

Speaking at the RAAF's Air Power Conference in Canberra today, General Bogdan suggested Australia was in a good position to profit from the servicing of F-35s operated by other countries in the Pacific region.

Australia can service its own planes as it sees fit, he says, but "what I would tell you is as the only partner in the Pacific when it comes to the future of what we do with other F-35s in the region, I would tell you Australia is in a pretty good position".

"Potentially Australia, if it chose to ... could be a place where other F-35s could come for work. Absolutely," he said.

The United States is expecting to eventually have 2,443 F-35s in operation.

The project has been beset by delays and cost overruns to date, but General Bogdan says many of the technical problems have been sorted out in the past few years.

Problems such as concerns over whether the plane could actually fly into lightning have been resolved, as has a problem with fuel dumping.

The JSF has also had a 100 per cent success rate in its weapons testing in the past few years.

General Bogdan says despite this, there are still some problems.

Reliability and maintainability in particular are not yet "good enough", he says.