You pay more if you go through a broker. I did mine on my own and paid exactly what is specified by the government, not a penny more. The last one I did cost $1500BZ for the year, the price has gone up since then.

When you renew your VISA at immigration after your first 30 days it's clearly stamped "Permitted to remain on condition that the holder does not enter into employment paid or unpaid, does not engage in any business or profession without the consent of the director of immigration and does not remain in Belize longer than the..."

If you are not a Belizean resident you must have a work permit to work.