When I was a young college student, I would donate blood plasma for money. For only two trips per week I’d receive a total of $75 in cash. Each trip took only took about 2 hours and as you long drank plenty of water and ate a healthy meal beforehand, you didn’t feel dizzy. I only passed out once, and that was because I was doing some serious physical activity. 
Your goal should be to make $75 per week per user the median reward level for Refer.ly

Good advice on how being genuine and not spammy helps to build your authority within your social network, as opposed to undermining it. Those particular examples are illuminating.