Anyone in aussie know the cheapest place in sydney to get there tongue pierced??

Do you want the "cheapest" place or the most healthy place?

The cheaper the higher risk of infection.

I second what J9 said. It's worth it to save up your money and get it done at the best possible place. Cheap will only save you money, the best will guarantee that you walk out of it with your tongue intact and your taste buds also.