IMHO, learn to do it yourself; get a guide if you have to. The key is using fresh, sharp, quality files, the metal will come off like butter; 1-2 strokes/tooth for a touch-up, and ~10 strokes/tooth for a "rocked chain". I can sharpen ten chains faster than I can gather them up and drive them someplace. Start with quality files, not the 2-pack of Oregon brand files you get at the hardware store; markup on those is 200% or more. You'll go broke buying them, or you'll be tempted to keep using them long past their usable life. I buy genuine Pferd (swiss) files from Baileys. IIRC, they are $9 or $10 per dozen, when they start to get dull they get chucked because I don't have time for a dull file.
This
Stihl sells a file set, do it by hand, easy and doesn't burn the chain.
I'll have to look into this.
I just bought a new Stihl and couldn't be happier with it.