Ertunc Eriklioglu, 31, his 27-year-old brother Samed and their friend Hanifi Halis, 22, are charged with preparing or planning for a terrorist act in November 2018.

After a week-long committal hearing at Melbourne Magistrates Court, Magistrate John Bentley on Friday decided there was enough evidence to send the men to trial.

The court heard they were planning "an attack on members of the public with firearms in a well-populated area".

In redacted documents released by the court, prosecutors allege the men were negotiating to buy an unregistered .22 calibre rifle to use in the attack.

Friends and family testified they listened to the teachings of al-Qaeda preacher Anwar al-Awlaki, wanted to go to Syria and had watched Islamic State propaganda.

Cousin Hakan Kirbas said the elder Eriklioglu brother told him he wanted to get strong enough to carry "big weapons" to fight in Syria.

He had also recommended Al-Awlaki's teachings to him.

"Everyone was listening to him ... even myself, until I found out he was too extreme," Mr Kirbas told the court on Wednesday.

Al-Awlaki was killed in 2011 by a US drone strike in Yemen.

Another witness who was a friend of the trio said they had shown him propaganda featuring the Islamic State flag.

They were focused on extremist ideology and a desire to travel offshore, a joint counter terrorism team officer told court on Friday.

Investigators initially assessed them as "aspirational" in their desire to travel overseas to engage in violent jihad, as the budding gardening business owners didn't have the means to do so.

However after November 12 last year, the "investigation changed course," the court was told.

They are expected to appear in the County Court of Victoria on November 29.

Australian Associated Press