I'm looking at a Thai Post Office collection form right now- I just had an external cellphone speaker sent from the States via USPS- it's not a large or heavy item, and I would usually expect something like it to be delivered without duty based on past experience- it was $100 total with shipping, and they hit me up for 900 baht import duty and 273 baht for VAT.
Normally I would have put a lower declared value on the customs label, but the shipper (like most of them) wouldn't do it as it limits his insurance claim if it had gotten lost.