You can earn money without investing dime, if you know good marketing skills.. At the start, i don't even spend $1 from my pocket..
I created account in BHW, hotmail & Paypal. I extracted contacts of my own from good niches.. As i'm good in SEO, i did some SEO proposal of my own and start promoted to those e-mail list. I got only 40% response and i can turn 20 - 30% as order..
First time, i got $700 from one client name "mike" and i spent $200 - $250 for link building service in BHW and remaining $500 for business development which includes my own private blog network, business registration, bank current accounts, etc.. later my sales goes very good like $1400, $2000, etc..
Now, I signed up one BIG deal of $12k (1st time) imao!! That project was actually "result reward" which i framed

. Upfront payment $12k and remaining after the result (if keyword reaches page 2, page 1, top 3).. Reward money will be % of share from his monthly revenue.. Expected revenue of client $75k, for me share amount will be 20%
So, i started business with $0 and i have $10k in my account right now. So anyone can earn money with SEO, Not only from SEO services, you can earn good money from other services like click bank, amazon, etc.. and only if he has good marketing ideas.