$70 will buy you a lot of chainsaw files! If you are only sharpening 5 chains once a season, just get a filing guide and a few files. Give the chain a quick touch up each time you refuel (you do let the saw cool down before refueling, I hope).

The added advantage of doing them yourself is that you can adjust the angles to suit the type of timber you are cutting.

Light travels faster than sound:
This is why some people appear to be bright, until you hear them speak!