It costs around $20 to take a taxi to the Muni from the Intl. If you are a group and your flight gets in early enough, it can be a reasonable savings. If your flight doesn't get in early enough in the day . . .it just isn't worth it.
Let's try to work this out . . . $46.50/person/oneway from Intl to San Pedro vs
$26/person/one way from Muni to San Pedro. So $20 difference, which is easily the cab fare. OK, that's one person, but you guys are a group. So has your group brought a small amount of luggage and so you will all fit in one cab?
Now let's think about the return trip. What time does your plane leave Belize City? Is it late enough in the day to find that you don't have to worry about getting from the Muni to the Intl?
Me, I'd rather be sitting in San Pedro either the day I arrive or the day of my departure, with my feet up drinking a Beliken, than trying to figure out how to save $15. Just my call . . .I'm not five people including a child.
A fish and a bird can fall in love, but where will they build their nest?