Sorry it is not the good way to ask this question, but I have no answer the official website. How can I order NexSXD board?
You can buy the board through the website because that's the only way to do it. The developers have posted a contact us email that you need to use in order to buy it.
Official website: http://www.nexsxd.com/NexSXD/NexSXD_eng.htm
Note: Make sure the subject is NexSXD or the email will be ignored.