Here are my basic rates:
$1.50/page: proofreading (this includes grammar, spelling, punctuation, etc)
$2.00/page: copyediting (this includes the above plus rewording sentences, suggesting new adjectives, inconsistencies, etc). This will also entail the creation of a style sheet for later editors to use.
$4.00/page: developmental editing (this includes comments about what in your story is working, which scenes should be expanded/cut, etc).
I'm happy to work with our indie authors on installment payments, and all of my proofreading/copyediting is backed up by a guarantee. If you find any mistakes, I'll go back in and fix it again at no extra charge.
I know it's hard to find good, cost-effective editors as an independent author...and not all of us can do it ourselves. If you're interested, you can contact me at email@example.com. Please use the subject line EDITING REQUEST so I can easily sort the emails.
Thanks, and keep writing!