Time is a valuable asset in SEO, and the longer it takes to invest in a thriving SEO campaign, the longer it takes to get free traffic. To answer the question, yes, SEO is a valuable investment and is worth the investment. You're creating an asset for your company by investing in SEO. Neither SEO nor PPC can guarantee you a place on the first page of Google, but, when done right, they can both help you get in front of your desired audience.
I hope that for some of those who read, they will now be better equipped to answer their own question of whether a paid SEO campaign is worth it for their business. I actually found a great company on Odesk, I tell them what I want to do and they do it, all “white hat SEO. But what if your company doesn't show up well in local results? That's where to understand what are the local SEO signals that search engines are looking for. The only common metric that every SEO agency puts on the face of every business owner who hires them is website visitors.
So, reflecting on the original question, “Is it worth paying for monthly SEO services? you have to consider what is at stake if your company is absent from search engines. When you compete with companies like 800 Junk who have a big SEO budget and several web designers on staff, SEO experts, it's tough and I agree, content is king, but off-page SEO is important if you really want to get to the front page. When I founded that company, I had a strategy in mind: building my business using SEO (or search engine optimization). In short, getting the right traffic to your website is not only difficult, but it can hardly be measured with SEO.
According to Wikipedia, “SEO is the process of affecting the visibility of a website or web page in the unpaid results of a search engine. In the golden age of SEO (which happened just a few years ago), you could easily target very specific keyword phrases. From this, you should be able to quickly determine what even a small increase in traffic, as a result of SEO services, can do for your revenue. Business owners and managers are often skeptical of search engine optimization (SEO) when considering their marketing budget.
However, if the SEO company is only writing a 300-word article to publish on your business blog, and it is very similar to the other billions of articles they published previously, it is very likely that you are wasting your money on SEO.