It cost 500 bahts each and they only take bahts.

Sorry, no experience with that

I apologize for not checking my box. The answer that I find very useful from the gentleman names Josh did a great job on Mae Sai border. I thank him in advanced. You have to know where you travel from.. Chiang Mai, Chiang Rai or Bangkok to Mae Sai / Tachiliek Border? There are Green buses ( air condition ) direct from Chiang Mai to Mae Sai. ( 5 hours ) and it takes 2 hours from Chiang Rai to Mae Sai. Now Ching Rai has an Uber and I am not sure it goes to Mae Sai?? You can find out from Trip adviser Forum. You have to check Uber ahead of time if you fly from Bangkok. So it will be ready when you land. The Green bus will not take all the way through the Border. The Bus terminal in Mae Sai is 3.10 miles from the Border so you have to catch the Song Thaews. It will cost 15 Baht per person..not sure the price now since 42 million Tourists had visiting Thailand in 2019. The new Visa Run for 6 months is in Chiang Mai. Sure?100% but go early to avoid a long line. James Hunt has a story about location independent. I Thank him in advanced. If you are in Thailand and get lost then ask around by using translate Page. The Thais are friendly and they will not hesitate to help. My opinion.

I caught a bus from Chiang Mai to Chiang Rai (about 3 hours) and then a local bus from CR to Mae Sai. Catch the Blue 9 minivan for 50 Baht with aircon rather than the local bus for 39 Baht. The local bus is slower and just has fans. I stayed overnight in Mae Sai and walked across the border. It's 10 USD or 500 Baht. Easy. The sellers in the market place weren't aggressive. Just say no once and that's fine. I did the same in reverse because I like Chiang Rai and I like to break up the journey. Steve S, you paid too much. 10 USD per person is fine and they were happy with my 10 USD, just don't flash it around.

If you have the paperwork correctly filled out and endorsed, you should have no problems.

You cannot get a boat from Mae Sai because the Mekong does not flow here. You need to go to Chiang Sai, which is about 30 km from Mai Sai, on the so-called Golden Triangle. You will see the long boats waiting for fares as you start to enter the town. An hour long trip up the river to Myanmar and across to Laos is 500 Baht. At one point you are sitting (floating) on the borders of Thailand, Myanmar and Laos. Enjoy.

Hi. A day trip to Tachiliek is possible as many Thais do this on a regular basis. It is done by locals mainly for shopping, and as you already appear to know, by foreigners wanting to extend their Thai visa.