I can recommend some good people. If you can talk more about your objectives, that would be helpful. One-time SEO is a good start, and might be all you want. But if you want consistent rankings, targeted results and good competitive information, this takes research and a long-term strategy, and generally comes at a respectable price.
I would actually recommend visiting searchenginewatch forums or SEOChat forums and watching for an SEO there whose style and comments you really agree with. If you have a high opinion of the poster, PM or e-mail them and see what they'd charge to do work on your site.
There are consultant SEOs who are worth their weight in gold and will only charge a few hundred dollars for a basic report - if you want someone to actually create content, links and modify your code to be optimized, that can be considerably more.