Looking for SEO/SEM Company. Long-Term Possible

I'm looking to strike a deal with an SEO Company. I'm looking for qualified people to hopefully build a long-term relationship with in this business. The company should be able to SEO our site for 10-20 keywords. None of these keywords have very difficult competition, as some of the keywords already are in positions 4, 6, etc with only one article on the website. The SEO Company shall be able to guarantee that 75% of the keywords given will be in the top 10 of [login to view URL] within 3 months as well as the exact domain match keyword show improvement (it is currently rank 6 without much backlinking) for $450 USD. If the SEO company cannot accomplish this, the company shall then continue free of charge until those keywords reach the goal of being top 10. I'm looking for long term partners in this business, for example if the goal is met, then I would prepare another website and keywords for another $450 with the aforementioned qualifications. Thanks! Hope yo hear from you.