Garmin-format maps are available here.
Maps are regenerated within the first few days of each quarter (Jan, April, July, October).
If you just want to try these files before starting a big slow download, then try downloading OSM-Belize-*.zip (2.5MB) first, which was created specifically for testing.
If you find any problems with them, then feel free to get in touch by email. Contact details below.
Alexis Huxley <email@example.com>