The real problem keeping you out of the property market may be the "exorbitant" price of coffee, Australia's most senior treasury official has suggested.

Under a grilling in a Senate estimates hearing Treasury secretary John Fraser said Melbourne had the most expensive coffee prices in the world.

He made that bold assertion after being asked if he had "upgraded" his advice on whether "millennials" were spending too much on extravagant breakfasts rather than saving for a house.

"I understand the issue," he assured the senators. "I'd prefer people to start talking about the exorbitant cost of coffee in Melbourne. It's got to be the highest in world."

But according to research company the Coffee Economist, Melbourne's prices are not even the highest in Australia. That prize goes to Perth with an average of $3.86 for takeaway cappuccino followed by Hobart on $3.73.

Melbourne's average price was $3.63 as of September last year.

Coffee Economist manager director Wayne Fowler said tough competition among Melbourne cafes helped keep a lid on coffee prices.

But Mr Fraser's choice of cafe may have influenced his perception of Melbourne's coffee prices.

Mr Fowler said that inner city cafes charging upwards of $4 coffee were cashing in on the café "experience".

That can include groovy decor, free Wi-Fi and even tattooed baristas. Add specialty coffee beans to that list.

"If you've got a hipster making coffee that's going to add a bit more to [the price]."

Although he did not have international data on coffee costs at hand, Mr Fowler said anecdotally Australia's coffee prices were among the most expensive internationally.

"Rarely I go overseas and pay more than I pay here."

The online menu at the Paramount Coffee Project in LA (set by Australians) shows a latte there will set you back US$4 ($5.20).

A column by demographer Bernard Salt in News Ltd on the weekend sparked fierce debate about those struggling to break into the property market after observing "young people order smashed avocado with crumbled feta on five-grain toasted bread at $22 a pop and more."

Shouldn't these people be eating at home, Mr Salt asked? He said that money could go towards a house deposit.