The thing with paying a percentage of what you would bring in, is that seo's are not associated with your site and we would have to go on a trust factor, and on top of that you might not see the results for 3 - 6 months in the which case we would not start see any revenue for that time.

There are a number of sites out there that can offer you tips on getting your site up yourself, or you should think of hiring a consultant. Then once you are making the revenue you and get too busy, you can hire someone to do your SEO for you.