With respect to the Phuket "sandbox", I'm surprised at the posts mentioning various costs for the three PCR tests (first one is at the airport in Phuket upon arrival and the next two are during your 14-day stay). I obtained the Certificate of Entry in the US and, in the process of doing that, I was required to pay 8,000 baht for the three tests (in fact, you can't get your final COE without uploading proof that you've paid for those tests). How I paid for them was via an url on the US Thai embassy website (I was unaware of any other choice) and payment was made to an outfit . Perhaps the costs vary for other countries but, for those coming from the US, it's 8,000 baht and is paid through some outfit named "Phuket City Development Co, Ltd."