On one hand, there is nothing wrong with being “value-conscious” and taking a more vertical and equitable approach to your business, “wanting to acquire talent for optimizing your website”; but on the other hand, quality and experience are typically commensurate to compensation.
This does not imply that in every instance that a higher price is indicative of better SEO. Due diligence is required regardless, but the propensity to find more supportive evidence (real rankings and conversion) is often more likely from a firm that services multiple markets to validate their prowess.
Similarly, if SEO is not a core competency it is not regulated or there are no standardized methods, so finding the right solutions relies on having a firm grasp of multiple disciplines.
The disciplines involved range from the most frequently employed platforms for web development and programming, a firm understanding of marketing and conversion tactics as well as elements of usability or user interface / design are a plus.
The bottom line with SEO is all about results and return on investment. So, when presented with the option to cut corners and make a splash vs. hiring a team with (1) a proven track record / history of results (2) a broader array of collective resources and (3) a firm that has SEO as its core competency versus a one man or woman show playing catch up in an attempt to compete, the odds are in favor of collective expertise.
Not to take away anything from In-House SEO or a few in house SEO acting on behalf of the company, but, if you are up against a serious competitor who understands the value of specialists, who has a coherent team with a larger optimization/internet marketing budget, any time you miss a beat, your likelihood of pushing them aside on the quest for keyword web estate diminishes exponentially.
When you do the math it boils down to 3 fundamentals (1) how competitive is your market? (2) how skilled are the players that dominate that market? and (3) what is your anticipated ROI?
If you are selling thumb tacks in bulk, then you may wish to consider a different tact (no puns intended). Products, systems or services with higher inherent margins can provide a more fertile ground for leveraging exposure using a pull-based marketing medium such as search engine optimization to build a brand, increase relevant traffic or test conversion mediums using a variety of keywords, landing pages or angles.
So, before you scoff at SEO services starting at 2K a month for targeting a competitive industry or competitive ranking, just think about how much it would cost you to hire an in-house SEO consultant.
Most consultants who are performing client work that are worth it, would consider a salary starting at 50-75K per year. Otherwise, they would just work on their own projects or use SEO for affiliate programs and remain self-sufficient creating their own websites and conversion funnels.
However, if you divide that cost by 12, minus, taxes, benefits, distractions and other costs, your options are simple; (1) what your anticipated ROI is and create a budget (2) learn SEO yourself (which is always changing) or (3) hire an SEO firm with the most experience that specializes in the services you need.