Postage costs vary immensely depending on the size and type of the packaging, if the parcel is insured (value of package effects this) and whether the package goes registered, surface or airmail.
A customer wanting polo tops or T shirts can estimate their postal costs from the Thai Post website thailandpost.
Prices here are in Thai Baht. At the present the the Australian Dollar is worth about 26 Thai baht or 36 baht for the US dollar. Registered Airmail will take about 1-2 weeks to get to Australia from Thailand
The average polo top will cost about 600 baht (AU$16) to send to Australia as registered airmail.
To send as surface mail the same package will cost about 75 baht (AU$2.00) Surface mail will take about 3-4 weeks to get from Thailand to Australia.
An accurate cost can only be determined at arrival at the post office and after the post office has weighed the package.