At the risk of being cliche, Cheap editing is not good and good editing is not cheap.
If you’re looking for a spell checker the going rate is about $.033 -$.05/word, so an 80,000 word doc will run you anywhere from $250 -$400.
Line-by-line edit—figure double the above.
If you want a “the real deal,” figure at least a grand. But the real trick is finding an editor who understands you and can give your work that little extra something that sets it apart from the rest. You’d be surprised at how many quality editors are available, editors who work with big names.
Formatting is a pittance, so inexpensive it’s not even worth a discussion. I have a formatting genius who charges next to nothing if you’re interested.
The bottom line . . . it’s not the cost. It’s the end product.
A large investment does not guarantee success nor does a small one preclude it.