Approximately how long will it take to bring my wife into the US from Australia using the following? If i file an I-130 or a K3?
You should speak to a lawyer about your situation, since there are some critical facts missing - for instance, your own status. I'll assume that you are a U.S. citizen for purposes of my response, but if not my answer won't be correct and won't help you.
As a citizen you could file an I-130 for your wife here; these take nine to eleven months in most cases. Upon approval, notice of the approval would be sent to the U.S. State Department and cabled to the consulate in Australia; submitting the final-stage paperwork and processing through the consulate there would normally take another two to three months. Total time: eleven to fourteen months.
Now, with the K-3: the I-130 would be filed same as before - but once we receive the Receipt Notice a couple of weeks after filing you can file the K-3 petition. however, since these take almost as long as the I-130 for approval, at most your wife would get here two to three months earlier than she would with the actual green card filing. Once she got here, she would need to file to Adjust Status here - about another ten months.
So, for the benefit of getting here two or three months earlier (at best), you are spending from $1,000 to $2,000 more in legal fees/filing fees/expenses and delaying receipt of the actual green card by about eight additional months. This is why I rarely recommend K-3 visas.
Speak with a lawyer about the best optiosn for you, given the facts of your (and your wife's) own unique situation.