How much money you will need?
All you need is a free email account and a free Paypal account; no financial investment is required. You may post your email and qualifications on EssayChat or similar websites.
If you want to get even more serious, a basic website (About Me / Services / Faq / Contact) may cost $100-$300.
You may also want to start working with a sub-contractor to revise/edit your papers.