Carmel Business Sales Nonpayment for website writing Carmel California

In early October of 2012 I was engaged to write website content for a new site by Mike Russell, the owner of Carmel Business Sales in Carmel, California. That site was for a Monterey in-home care service called Caring, Loving and Sharing, 15 site pages total. I'd sent a proposal to Mr. Russell that outlined the scope of the project, my writing responsibilities, and my bid, for $2,000. He came back with an offer of $1,200. We discussed it on the phone, and agreed to $1,700 for the completed project. My mistake was in not getting a signed contract, either on paper or by email, but since he had agreed, I worked on the project in good faith.

I received an initial check in late October for $550 after most of the site material was completed. I received a second check in early December for $550 long after the fundamental writing was completed, but I was told that the company's website person was late in posting the material, thus the delay. In the meantime, I edited a brochure based on my site material for free. In late January, the site was fully online, and I sent in my final edits on February 1, along with my final invoice for the $600 balance. 

No response.

I then sent him a number of emails over the next couple of months—all mild in nature, just inquiring why no response. No reply whatsoever. There had never been any friction between us over the course of my writing on the site, only responses of "good job!" and some editing discussion. So, he is now six months in arrears, with me having sent him a number of reminder invoices, never with any harsh message. I also sent a certified letter with an invoice, but it was sent back to me unopened. 

My request is simple: that he pay me what I'm owed, for the work I did in full.