I'm going to need an SMS sender site, where people can signup for free with email confirmation, and they can login with SESSION-s.
On their account home, they see available credits, and etc.
They can also refer others with a unique referral link (userid)
It should be a simple script, handling only the signups / logins / referrals, I will do the rest (handling sms, credit uploads, etc).
Should be done in mySQL / php.
Max budget is $40