Hello, Every SEO has their strengths and weaknesses. You wont find these factors until you hire them and find out for yourself. Just because one seo worked for your friend or another company, doesn't mean that same seo company can perform the same for you.
I came across a company called iMajestic. They have a performance based package which states that there is no setup fees, and you dont pay anything until you rank in the top for the major search engines. I'm sure your site has to qualify for such a campaign but it wouldn't hurt to give them a call and see for yourself.
To me the best SEO is one that can perform. No matter how much they talk, actions are louder then words. Why pay upfront when you can pay when you get the results. check out their website for yourself if you're interested in pure performance Search Engine Optimization;
iMajestic - Internet Marketers