Looks expensice but it is still a good price when you consider how much time and money you'll spend to get other visas multiple times to make the 6mth period. Sure new guverment in NZ can do smth about it if we ring the bells to local MPs. Same with Vietnam and other asian countries.
Don't do it. If you plan to re-enter Thailand keep it simple and do not complicate your situation. It is very easy to get a new visa anywhere outside Thailand if you don't give them a reason to think