Proofreading should be the very last level of editing done before publishing your book.
I’ll look for spelling errors, punctuation errors, missing words, and repeated words.
I’ll also ensure consistency throughout your manuscript, checking to make sure ‘smart’ quotes are used, that Chapter One is followed by Chapter Two instead of Chapter 2, etc.
$0.004 a word, with a turnaround time of 24hrs per 20k words. There is a flat rate of $40 for manuscripts that are less than 10,000 words.