Boten
Boten (Lao: ບໍ່ເຕ່ນ, Chinese 磨丁) is on the Lao side of the border between Laos and China. You can cross the border on foot.
The timezone changes at this border. Going from Laos to China it becomes one hour later. Coming to Laos from China it becomes one hour earlier.
Arriving in Laos, the border officials might come up with any number of reasons to squeeze an extra dollar or two out of you.
A Laos visa on arrival costs about 30 US dollars, depending on which passport you carry.
There is a large duty free shop with official money changer on the Lao side on the left before the customs and immigration area. The building has a sign saying it's open until 10.30pm, but the money changing service actually closes at 6pm. There are also black market money changers on the Chinese side.
If you cannot pay in US dollars you may be overcharged. In 2015, Hippietrail was told 250 yuan for the visa although the true exchange rate would be 205 yuan, but managed to haggle it down to 220 yuan.
On the Lao side there are a couple of supermarkets, restaurants, and street food. Prices are in Chinese yuan and are not inflated. The Lao food seems to be cheaper than the Chinese food. A delicious bowl of noodles is 8 RMB.
If you need to sleep here there are cheap hotels from 70 Chinese yuan with aircon, Wi-Fi, and hot water. It's very easy to haggle the price down an extra 10 RMB. There is a former casino several large hotels in various stages of completion which were (semi) abandoned for a few years and it was feasible to find a place there to camp the night for free. But there is once again lots of building going on here as of mid-June 2017 and most of those buildings are being worked on or are housing the workers. There seems to be prostitution and perhaps gambling, etc. Try to stay safe if you decide to sleep in this area.
You can continue further into Laos to Luang Namtha or Muang Xay (aka Oudomxay).