I'm with Tom and Mark.
I found that when we sent the chain off, we were spending close to $20 and they were grinding a lot of steel off the chain. So I started filing my own right on the machine. Takes 5 minutes, costs practically nothing and I always have a sharp chain.
I use bar and chain oil. It is cheap and it is made for bars and chains in that it doesn't get slung off. I put it in an empty chalk bottle.
I have seen the Ryobi, but not used it. Having seen it, though I would not want one even if it were cheaper than the Makita.
Cheers,
Gabel