I read an article that says Lucky Air now offers direct flights from Kunming to Koh Samui, but I can't find that flight listed anywhere online. I've checked Ctrip and Elong, and also Lucky Air's website to book this flight, but no search shows the flight. Does anyone know if the flight is up and running, and if so, which days do they have this flight and where can you book it?

Recommend you call them, it usually takes a little while for the flight to be registered in all the systems/with all the authorities. Even though they may be flying there is usually a lead time for them to appear, but usually you can book over the phone or at their office. Strange though that it isn't even on their own website!

Ko Samui or often simply Samui as it is referred to by locals, is an island off the east coast of the Kra Isthmus in Thailand.

I asked today, and the price was 3,700 RMB for a round trip ticket. That was for the middle of next month. Which is roughly the same price as a ticket with a layover somewhere else.

If you have time it's much cheaper to fly to Bangkok and then take the scenic route to a ferry somewhere.

And the Chinese name is Sumeidao苏梅岛

I'm not sure about lucky air, but Air Asia worked best for a few flights I took in and around Thailand earlier in the year. They fly KMG to Bangkok DMG and from there is should be easy enough to get a cheap domestic to Koh Samui. Sorry, I've got no better info on a direct flight.