I've heard it so many times before!
Just because you are self-publishing your book does not mean that it is a good idea to self-edit it. In fact, I would argue that self-editing is ill-advised at best, and a really bad idea at worst. When you have spent months, nay, years, writing, you can read your story in your sleep. Your brain will see your manuscript as complete and perfect every time. But your brain is wrong! That's where I come in and fix all the little things that your brain skims over...Punctuation? Check. Spelling? Check. Subject-verb agreement? Check. Comma splices? Check. Incomplete clauses? Check. Dangling modifiers? Check. Shall I continue?
The best reason I can give you for hiring a second (or third, or fifth) pair of eyes to go through your manuscript is money. It is so much easier to sell books when your readers are not completely distracted by typos and other errors. Everyone can see them, not just grammar queens like me. Would you rather give away 500 free books, just to get reviews that say, "Nice story, but you need an editor," or would you rather sell 500 more books because the freebies introduced a professional writer with an intriguing story to tell? The difference between a professional writer and just a writer is an editor. I'm here when you are ready! (Now I'll let my proofreader look this over before posting.)