NOTE: Use with caution. As of 7/25/2013, I've just read complaints online about them not paying and possibly being scams. I recommend not paying for any premium services in case they are.
I haven't paid them anything for the premium services and am waiting to see if they actually pay out. The 60 business days until payment, along with a few other contract terms, is pretty suspicious. I have a good deal of free time while recovering from an ankle surgery and nothing to lose from trying them. I'll post an update about the cash out process later.
My referral links:
UPDATE: (4 am Eastern on 7/25/2013)
I searched more online and found more disturbing information to suggest that these and similar sites are most likely scams. Avoid paying them and file complaints if you have problems.
1. ScamBook Complaints about Seven Dollar Click: http://www.scambook.com/company/view/28713/Seven-Dollar-Click
2. ScamBook Complaints about Two Dollar Click: http://www.scambook.com/company/view/2258/TwoDollarClickcom
3. ScamBook Complaints about ProperPTC: http://www.scambook.com/company/view/15724/ProperPTRcom