There are various, equally poor options available:
1) Bring her over here on a student visa. Colombia is assessment level 2 country for most of the student visa types, so it is possible.
http://www.border.gov.au/Trav/Stud/Stud
Better to turn to a school agent, who deals with Colombians. They know more about the traps.
While over here you learn about each other more and may even marry and lodge a spouse visa on-shore. She may start work as soon as the student visa expires, so there is no point to apply for a lengthy visa.
2) She may lodge a Subclass 300 application right now, then a visitor visa application soon after. The Subclass 300 applicants are usually dealt with more kindly when applying for the visitor visa. However, trusting the kindness of the Department, well, it is a risky process.
Let's assume, that she will get the visitor visa. Then she may not work at all and has to leave Australia in 3 months time. The waiting period for the Subclass 300 visa is much longer, it is about a year, so you may try to extend this 3 months waiting somehow. One way to do it is to leave for a few days for Bali, spend a little honeymoon there and return. Then the visitor visa kicks in again and gives her further 3 months. The problem is that she might be turned around at the border.