I'm surprised by these comments, this is not my experience at all.
Quoted $20k in Australia I will get the work done here for $8k.
I think you will find general work is cheaper, crowns, extractions, etc. But obviously one or two operations will not make up for the flight and accommodation.
When it comes to implants, I think you will find that maybe it is only slightly cheaper, say 25%, but what you may be missing is that the technique is more advanced, for instance they can do 'all on 4' which is a row of top or bottom using only 4 implants, whereas in Aussie you may find that it takes 6 implants, (therefore more money and pain). I also can't see how you will get the care, professionalism or time over quality either - no rushing, consultancy and decision making is free in Thailand - not so in Aussie.
There are also lots of extras that you will get burnt with in Australia, for example a bridge may involve 4 extractions and 2 crowns, this is where the cost mounts up, whereas when you take that into account in Thailand, the total is more likely 50% cheaper.
I'd suggest you look again and think about the entire package.