Bailey's is great, but whether you buy and extra chain or two or three won't change the question of keeping the chain(s) you do have sharp. People who cut regularly, and even some who don't, value a sharp chain, which will give your saw performance equal to a larger saw if your chain is dull.
The price for sharpening around here [Denver and surrounds] is $8 or more for a 20" chain. I mean, of course, a chain for a 20" bar. I haven't had one sharpened by anyone other than myself in several years, but the last time I did it was $8.
A good file is a couple dollars. Or less sometimes in packages of three or four. If you learn to file, you will start each day of cutting with a sharp chain. Or if you decide to go the grinder route, same deal. The sharpening equipment you buy will pay for itself. If you go the hand-filing route, it will pay for itself in two or three or only a few sharpenings.
But, yes, get yourself a spare chain or two, regardless of what you decide about sharpening. Bailey's has some screaming deals, though the shipping on an order of one or two chains is probably a nod toward buying them locally. Of course, Bailey's has lots of other stuff to consider besides chains, like spare rims and sprockets and bars and files and so on.