I wanted to send a pair of pants to the US; Thai Post said it would cost 360 baht 3-4 weeks, which seems both slow and rather expensive. This is excluding packaging. Is there a more reasonable option?

No, any private carrier (DHL, FEDEX, UPS) is going to be more expensive

Is the 360 THB figure via EMS or just regular surface (not airmail) post ? I ask because EMS is slightly more expense option than Thai Post

Input the weight (kg or g) of the pants here and see all your options and prices but you must include the packing in your weight total

http://www.thailandpost.co.th/rate-result.php

EMS for a letter to the US is 600 baht.

10 bucks to send a parcel halfway around the world is expensive ??

360 baht is expensive as it takes away from the balloon chasing fund.

Theres a fund now ?? Why wasnt I told..

He has it in a dish of coins in a dirty corner of his hovel.