Nah I would pay a lot for shipping to get some authentic Thai sticks. lol however I asked chatgpt how much and it says:
A one-ounce letter or postcard sent internationally with USPS First-Class Mail International costs $1.50. This price is for a Global Forever® stamp, which never expires.
To send a letter from the United States to Thailand, you can use Global Forever Stamps. You can also use regular, domestic forever stamps as long as they add up to $1.50. Extra postage is required for letters over one ounce.

I'm assuming from Thailand back would be the same. I do a lot of international shipping and a pound or two usually costs 20-25 bucks to ship, rates are not that bad actually.