Your budget is unrealistic for what you expect to achieve! You should be willing to pay at least $1.00 a page, which might make the job worthwhile for an experienced proofreader. I could proofread for spelling, grammar, punctuation, and inconsistencies for that figure, with a realistic deadline for completion (124,000 words should work out to about 250 pages, depending upon font, spacing, etc.).
FYI: Proofreading is not a scan job. It is not a "read for entertainment" endeavor, requires close attention to detail, and often requires more than one reading if the job is to be thorough. Your project sounds interesting and I would like to help with it if mutually agreeable terms could be negotiated.
Thank you and good luck!
BAProofreads