I'm planning to get married in AC next year. From what I found, if you do the paperwork yourself it's about $110US.
If you have someone else do it for you (ie, go to the courthouse file and then go back a few days later to pick up license and get it to you & Notary), another $100-$150. The courier service is great if you happen NOT to be staying in Belize City or Belmopan. These are the only places you can file for a license. As far as a minister, I've gotten quotes for about $150. Are photos included in your package?