Here's a link to an article on Dante Exum. Don't freak out at the pics, it's just his high school team name, Lake Ginninndera College:
Dante Exum urged to enter NBA draft
Also, by way of background, way back in 1976, Australia went to the Montreal Olympics and came back with one Silver and 4 Bronze medals, our worst result ever. And the sports-mad Australian public was all "WTF?" and the Government said, "no worries, we'll create a training institute for elite athletes so we can win Olympic Gold medals" and the Australian Institute of Sport (AIS) was born, running elite training programs for a variety of sports. The Canberra-based AIS offers scholarships to young people with potential to play basketball for Australia. They attend a local high school, but go to daily basketball training sessions at the AIS which are closer to college-level training. The AIS also entered a team in the second-level men's national league, and top-level women's league, but recently scrapped these teams in favor of making a number of overseas tours each year, playing over 40 games annually in a series of tournaments.
A number of AIS graduates have gone on to play in the NBA. The highest-profile AIS graduate would be Luc Longley, and current NBA players Andrew Bogut, Patty Mills, Aron Baynes, and Matthew Delavedova are also AIS alumni.
So, even though Exum hasn't gone to college, and may not go to college, he has received college-level coaching at the AIS for three years, and has played in games against senior competition, including playing for the Australian National team at both junior and senior level.