Hello Mike,
Welcome to the forum; there is a wealth of information here about DW's. I'm actually the sister of the bride (that got stuck planning the entire wedding), but I am more than willing to share any information that I can about Cancun if you would be interested. The cost of a DW really depends on what you want & how many guests will be attending. We are having 25 guests & for everything (food, open bar, site, judge, papers, bloodwork, photography, cake, flowers, etc) we are paying close to $5000. Most of the resorts offer a free wedding coordinator when you book your wedding with them. My favorite resorts in Cancun to host a wedding would be Dreams Cancun, JW Marriott & Casa Magna. Dreams Cancun, I think offers the most complete wedding packages at the best prices, but they didn't have our date. If I can be of any help to you, please let me know. Have a great day & good luck!
KIM