Cablemas (which services Chetumal) offers 100 mbps download and 10 mbps up for about $145 USD per month. Their cheaper plans are even much faster than here.
http://www.cablemas.com.mx/Productos/Internet.aspx

That's roughly what I pay for 1 mbps from Coral Cable and the internet goes out on almost a daily basis here. Gonna have to see if Electric Dave can run a line into Mexico for me and tie in up there...