I'm adding to this topic because it comes up in Google search, I hope the information is useful to others...
Dr Anywhere (telemedicine app) can provide Zolpidem at 30 baht per tablet, you must first consult with one of their Psychiatrists which costs 1500 Baht (quite expensive but you can't beat it for convenience) all done from your phone/tablet and the medicine will be provided by courier service.
In my case, I uploaded referral letter and medical notes confirming long-term use of Zolpidem..... It is possible (and quite rightly) they may not be happy to prescribe this drug without first trying alternative options...