I assume if Thailand is like other places, the tax is determined by the item, not the cost. In other words, the tax on bringing in a motorcar is not the same as the tax of bringing in a computer.... and then you have the added confusion that many many item can be looked at differently by customs officials... if you bring in drinking glasses, it could be viewed as kitchen items, glasses, items of glass, or crystal.. and each might have a different rate of taxation... that is how it is in the USA and probably here too...