If you want a very basic ceremony, I would think a local clergyman could be hired for a hundred bucks or so?
The problem with a local clergyman is that they are only able to do the religious part of the wedding they cannot preform a legal wedding in Mexico that takes the local Judge.
Well, the ceremony is just a ceremony, it is not what makes a marrage legal, the paper work does. When we got married, going on 24 years ago, our preacher had us sign our marrage certs. before the wedding and told us that we were "officially" married at that point, the ceremony was really just something to make a public statement of our marriage, so to speak.
Go to the JOP here in the U.S. and get the paperwork done, then go to Coz and hire a local clergyman/woman to do you a ceremony on the beach.
I don't know where you stay, but DM Jose at Blue Angel is a priest, I don't think most people know that.
Also, we went to a church for Easter one year down there, that I think is a Presbyterian church it's located on Ave. 30 (north), they do non-denominational services, the preacher is an American woman, very nice, she could possibly help you out.
Also, Also, there was also a young American preacher that was doing a start-up church in a storefront along Calle 11 Sur (11th street south), but I'm not sure where they are now. You could contact Lisa at Rock-n-Java (the owner), she was attending that church when we went there a couple years ago.
Hope this helps