If you have a solid website but no one can find it, it serves little purpose. Companies hire my to reset their SEO so they can achieve higher results in search engine rankings. I only work in organic search results instead of Adwords. When it comes to building a solid website for SEO, content is king. Google will reward your website for being the master of its subject matter. In the last 10 years, I have never advertised. My website SEO brings in new clients weekly. You might be one of them.
My pricing for SEO is based per project. Most companies require two to four projects, content changes, and reporting. Each round of SEO is measured and invoiced and then it is up to the client on whether they would like to continue forward or if they are happy with the current results. I have worked on small scale and large scale SEO projects for websites that range from 100 visits a week to 30,000 visits a week. My SEO invoices are sent with detailed reporting about my findings. I try to give as many answers and as much power back to the client as possible so they can decide where they would like to go next in terms of SEO findings. There is no website too small or too big for an SEO review. When the SEO foundation is set up correctly, it can cut your marketing campaigns and monthly advertising budgets significantly.