Just want know, how many bath can one person export outside Thailand ?

One person!

Are for Thais same limitation then for farangs?

How high are the fine when someone export more money then allowed from thai?

Why are this limitation nesarsary?

Are the also any declaration nesarsary for import money?

My gf told sale of banknotes not allowed

In Thailand, but on eBay USA I see many money traders from Bankok with 5000 and more feedback selling many years!

What see the law about this in detail?

at the airport it is 50,000 BAHT or the equivalent in cash per person if I remember correctly.

If you have a work permit you are allowed to export up to your net earnings each month. Without this you are best advised to change your money here at SuperRich and then carry foreign money out of Thailand. Note that USD is stated on the customs declaration alongside THB so choose another currency that you know you can get a good exchange rate for in your own country if you are American.

You can transfer $20k without having permission via your bank but never tried it.

there is no market for thai bath's.

there is no market for thai bath's.

except in very dirty countries.