This is really free to start, they do give you the option to buy more MH/s .
They charge $1 per MHs, if you choose to buy I would advise not to spend more than $20 because that will be enough to earn 0.1 BTC per day, they also have a Calculator for you to make your calculations .
They give 3MHs free so you can start Mining straight away .
I also checked the site to ensure it was not a Scam https://goo.gl/9F8q2f
