Which countries provide visas at the Chinese border upon arrival? I've read that Laos at Mohan-Boten does. Are there any other places?

Try Google?

Yes, I have. I seems that Laos at Mohan-Boten will issue a visa upon arrival.

There's only three countries bordering Yunnan.

Foreigners are not allowed across the Myanmar land border anyway. That leaves Laos and Vietnam. Vietnam allows some foreigners in without visas for two weeks. You have to check the conditions for your nationality. Laos gives visas on arrival at the border for about 50 US dollars

Thank you for your help :-)

The Myanmar border is currently only open to Burmese and Chinese citizens on short term passes traveling no more than a few km inside each other's territory. There has been talk since 2013 of upgrading at least the main Ruili-Muse crossing to international status and allowing locals and foreigners through with appropriate visas.

Until the Burmese side sorts out the security situation, particularly in the Kutkai area (which is a village located on the highway a little south of Muse) then the border can't be upgraded.

For Laos, VOA is possible though some nationalities are visa exempt. Vietnam is visa exempt for 15 days for ASEAN nationals, Nordic nationals, UK, Spanish, Russian, Korean and Japanese nationals.

Some nationalities cannot get VOA at the Lao border. Last time I was there, about a year ago, these included several African countries and Turkey.

Voice of America?

Visa On Arrival.

Probably the voice of reason mate