5,000 backlinks for $5. When you send them their report, give them 6k or 7k backlinks so they are happy that they got more than what they paid for. Then upsell them on additional services you offer. If they are happy (which they will be if you completed the job promptly and over delivered), then some of them will order your upsell. It could be a linkwheel, pyramid, article blast, whatever. While fivver may only be $5 services, you could increase the average per customer to 15 or $20 if every couple people order your upsell.