Note that the airport isn't all it's cracked up to be. It does not have many direct flights to the major cities, with most flights requiring a multi-hour stopover in Kunming.
A lot of the people I know in your situation opt to hire a car to the Lijiang airport or straight to the Kunming airport and fly from there. Now you can also get to downtown Kunming in two hours via high speed rail, another option, though it takes another 30-40 minutes to get to the airport from there.
That official agency people are mentioning is really only useful if you need a notarized translation to hand into a government office, like an official translation of your passport or driver's license. Avoid them if you need to actually communicate something clearly.