@Johnny ********

can I just be a hopeless romantic mate? :)

I can comment on the 25k for the sc600 application as that is what i do for a living. It is reasonable (although i know it does not sound reasonable for many) and is quite an average number when it comes for sc600 applications for high risk countries. The goalpost has been moved by the department and the evidence required is more complex than a mortgage application. Your Au partner visa would set you back around $15-20k (that is AUD) depending on complexity. Love appears to be real expensive these days.

I cannot help you with the USA visa part. I am am an Australian Migration Agent and i can share some experiences as the US and Au are both pain to get into. In general, when i work with anyone from a perceived "high risk country" i prepare a very detailed submission with regards to incentives to return; address things that the Au government deems as genuine temporary entrant criterion (from local assets, family ties, long term employment and so forth). I am going to assume that this is similar to what the US want to see. You need to very much emphasize that you are going to visit, but you both reside permanently in Thailand and intend to do so in the long run. Best of luck