I completely disagree with most of the replies.
Having someone edit your work can be very valuable even if the work itself is not publishable. Not only can it make your manuscript better, but it can be a learning tool much like taking a class, reading a book on writing, asking questions here, etc.
I'm lucky that my wife is good at editing. Having the extra pair of eyes that can spot weak points in writing, tendencies that I might not have caught on my own, as well as possible issues with plot and characterization has been invaluable. I have become a better writer because of it.
Also bear in mind that no matter how good your story is if your writing stinks it is not going to get published (outside of vanity press). I'd bet that well over a half of submitted manuscripts are rejected within the first few paragraphs -- and that's because of writing, not story. (You can't rightly tell much about story in a few paragraphs unless you are reading a short short!)
How to go about looking for an independent editor, if that is your choice, is a totally different thing. There are definately a lot of scams out there and you want someone that is going to be geniune in their work and good at documenting the needed changes in such a way that you can learn from the process.
However, I would say hiring an editor is definately something you should do after you have read multiple books on writing, taken any courses you can on writing, written a fair amount of work yourself, and if at all possible joined a strong writer's group. (In many ways a writer's group can give you the same help an editor can as far as what you can learn from them.)
But I wouldn't completely write it off.