One of my biggest challenges in getting my book published is actually proofreading. Proofreading to professionals is clearly the gold standard, but I thrive to be frugal so I ask family and friends to proofread my book. That way you also get feedback about the book at the same time. I believe the energy of GOOD friends and TRUSTED family members add to the ‘energy content’ of the book, which I hope in return will attract the (right) readers to it too.
My daughter Erica is possibly the best proofreader I know. She beats 15 other people (including a paid professional proofreader) on picking up my mistakes.