SEO for small business? Like really small?

Ok, I found a site that claims to be able to SEO a site for under $100 a month. Automated system that kills it for local sites. I'm working on figuring out whether or not it is true. If this thing works, it could be awesome for local biz that can't afford typical SEO service. I'm checking it out. If it works, I'll publish it. If it doesn't, these guys are big fat liars. I'll let you know.