We spent 8 days in Belize and spent a total of $381. That means that we spent on average about $47 per day. However, this is “cheating” just a bit because we heard that gas was much more expensive in Belize than it is in Mexico, so we filled up before we crossed the border and never had to fill up in Belize :).
Our largest expense was food ($206), followed by entertainment ($93), and then living expenses ($51 – all camping). We found ourselves cooking a bit more in Belize than we had been in Mainland Mexico, mainly because we missed Mexican food and our campsites were pretty remote. Camping was incredibly cheap because we spent at least half our time in Belize boon-docking.