Using an excerpt from your manuscript (in SMF), I'll do a sample edit and provide you with an estimate. I charge $28 per hour and ask for a deposit to save your spot and to cover some of my hours.
The actual price could go up or down, depending on what I find when I edit, but the estimate should give you a general idea for budgeting, and I'll of course communicate any noticeable changes so there won't be any big surprises. Please note that a couple of additional hours are included in the estimate to account for a critique letter.
Keep in mind that how long a manuscript takes for me to edit is not always an indicator of how "good" or "bad" a story is. While cleaner manuscripts will go faster, some stories are inherently more complex than others and may require more time to edit in order to meet the author's vision and goals.
Note: The Editorial Freelancers Association offers typical rates in the industry here. Keep in mind that they can still vary widely depending on the project, editor, and what the writer wants. Also worth noting is that editing terms can sometimes be ambiguous in the industry. For example, developmental editing and substantive editing have been defined each in different ways, and sometimes, elsewhere, as even the same thing. Same with proofreading and copyediting. So make sure you communicate with your editor.