I have to pay $8 to $10 per chain sharpening here and drive 35+ miles to drop them off and again to pick up. I finally bought a Maxx grinder [you can find them new for maybe $350 on sale]. It paid for itself in a couple years. I have three saws and use them regularly as we heat with wood. The convenience of having the grinder in my shop, right here at home, is also worth something. Plus, I was tired of taking a chain in to be touched up and having it come back with the teeth ground down a quarter of the way. I am getting ten times the life now doing it myself. Add in the cost of new, good-quality chains and that's another benefit.
I haven't used any of the cheap [HF/Northern/other China knockoffs] versions, but friends who have all tell me, 100% if them, that they wasted their money or spent lots of time and effort "rebuilding" them with better parts and etc. to get them to work well.
I hand-sharpened for 25 yr. and still do some, but I really like the grinder and should have bought one earlier. The Maxx isn't the only decent one out there, and there are some incredible ones if you wanna pay a thousand bucks. The $300 to $400 models are a good compromise for the non-professional wood cutter.