You could hire just any copy editor. Or you could hire someone who's been copy editing as well as editing (big difference); writing (ghostwriting, copywriting, speech writing, etc.); typesetting; and publishing in various capacities since 1993.
I mean heck ... did you see that crazy use of: etc.); in the paragraph above? And why semi-colons? Because there were commas within the parentheses. And yet, this is technically a "house style" issue. I could have used a comma after the final parenthesis (singular of parentheses), and those are the kinds of style issues that need to be determined at the beginning of a project (if you have a preference) and kept consistent throughout an article, story, or book. That's one of the many jobs of your copy editor.
If this is all confusing to you, don't worry. This is only to say that you can go out and cheaply hire someone to look through your work and probably still not get it as clean as it needs to be. (Many people online will simply "proofread" while thinking that they are copy editing, and this is why they charge so little. They will only pick out the most glaring errors.) Or you can hire me for standard professional rates and get truly professional results.
To be clear, copy editing is NOT editing. Editing looks at your overall structure and helps you to improve your writing in a "big picture" way. Copy editing simply makes sure that your writing is free of spelling, punctuation, and grammatical errors while maintaining consistent usage throughout a work. It also makes sure that your text makes sense. So a good copy editor will, in fact, edit a sentence to get it clear.
I charge 1-4 cents per word for copy editing, depending on the quality of the writing initially given to me. If the copy is pretty clean up front, I charge just 1 cent per word, and a 1000 word article can be finished for $10. On the other hand, a book (let's say 70,000 words) with spelling and punctuation errors throughout could cost $2800.
So please feel free to contact me so I can look at your work and give you an exact quote. Thank you!