Well to be honest, I would use a file and keep the chain touched up, and if it gets to the point of needing to be put back in top shape have it resharpened by a sharpening service. ABout every 6 or 8 file sharpenings I have mine redone on a machine. I cut wood all year around, while I don;t have the frozen wood anymore to contend with, I do have a lot of wood thats pretty dirty. I stay away from saw chains sold in places like wal mart and builder supply stores expecially those that are touted as being hard chrome plated for long wear. Commercial chain is not chrome plated, and it will outlast a consumer grade chain by a long shot, but you will have to go to a place that sells commercial grade chain. Lots of commercial grade chain does not have all the safety features in it like consumer chain does, so just be aware of that. Commercial grade chain will outcut and last longer than consumer grade will. There is a place called Baileys on the internet that sells their own brand of chain named Woodsman. Its some super grade chain, and is actually made by CArlton Chain which is a spinoff of Oregon chain. Carlton chain is some top grade chain, and IMHO better than Oregon brand. So don;t be afraid of the house brand Woodsman as its actually Carlton brand.
Learning to file a chain is not hard, but its easier if you have a person that knows how to do it show you first hand. I have never owned a machine to sharpen chain and with the amount of wood I have cut and continue to cut, I still can;t justify its use, when a file is fine. Folks usually keep forcing a dull chain to cut, which makes it harder to put back in shape. Check your bar for wear as well as your drive sprocket or spur. If you have a symetrical style bar, flip it over each time you sharpen the chain. If you went threw 2 or more chains already odds are you need a new drive spur or sprocket. Check and see if a rim type spur can be installed on yur saw if your in need of a new drive sprocket. They last a lot longer than any sprocket, and chain will not jump off as easy if the bar gets in a twist. When replacement of a rim is needed its only about $3.00 for a new rim instead of $20 + for a new sprocket.