As a case in point, airfares to Belize have gone way down in recent weeks. When I started planning for this Summer's field season, airfares were nearly $800. I bought my tickets when they dipped below $700. I bought too soon. Tickets are now a little over $500.
Example for a flight leaving Tulsa on June 20 and returning June 29:
If you are ready to purchase, I think this is a good time. Please check with me in advance for tips and tricks (e.g., Continental includes taxes paid to both the U.S. and Belize, while American only includes U.S. taxes, leaving you to pay ~$40 upon departure from Belize).