You may consider buying an aftermarket brand new headphone with some resellers on eBay. Yes you will pay a few dollars more to the reseller’s profit, but at least you will get the HD58X you desire. I just checked on eBay and I found many « new » HD58x between 200$-230$, and a few « used » in good condition in the 150$-200$ range.
How can I in Thailand order this, then? How do I contact Massdrop about this?