In about 3 months, the rankings on the keywords increased by about 4-6 positions getting from page 2 to page 1 and the cost was very reasonable. Now I know what a lot of people on here are thinking right now, this guy must be associated with RankPay. Nope. The results were mediocre, nothing close to spectacular. But they WERE results, and they ended up being cheaper than having me do manual link building myself (which the client couldn't afford).
So while as I wouldn't consider RankPay a 'replacement' SEO service, it might help offload link building activities for some SEO's working on limited budget projects.
One thing to consider is if you are doing SEO for thousands of websites, then you can run reports across all clients to figure out what is working and what isn't a lot faster/better than an SEO working on 3-5 websites. Many SEO's hate RankPay simply because they are 100% pay for performance and most SEO's like to reiterate the fact Google is unpredictable so they can't offer pay for performance. I personally offer a blend with my clients in the form of a 'ranking bonus' which is a sliding scale spending on how high I get them. Otherwise, the SEO is putting 100% of the risk of the unpredictability of the SERPs over time on the client, and I don't think that is fair. Nor attractive from my business owner perspective.
So I haven't used RankPay in a while now because I haven't needed them on any recent projects. Wondering if anyone has used them lately and how they have performed for them. Obviously your mileage may vary depending on many variables (state of your website -- they don't do on-site SEO, competetiveness of the keywords, amount of time you've been with them.)