Can someone tell me how much the weekly rate is for the water taxi pass?

its more cheaper gettin a golfcart than water taxis caus with a golfcart you can travel anywere

I don't agree with that at all. The golf carts stuck in the mud and abandoned along the road are quite a testament to the contrary.
This would very much depend on where you are staying.
The island is long and narrow with most of the hotels all along one side. The water taxi goes up and down this side and stops a all the docks along the way. A very convenient way to travel the island.
On the other hand the roads are mud with holes, not navigable in the rains ...and this is the rainy season.
weekly passes on the ferry vary according to where along this long skinny island you are staying, but all cheaper than a golf cart.

Not to mention getting eaten by mosquitoes. I wouldn't choose traveling unlit roads with pot holes and mud holes.

Let's see,hundreds of dollars a week. Not to mention the bill for the Chiropractor and everything Amanda said. Weighed against a 20 min. +- trip for between $40-65 dollars a week. Coastal Express please...

On the other hand, there are some who, when traveling to Placencia -- or to Chicago or Sacramento -- would rather rent a car rather than wait for a bus, even though the bus is much cheaper.

It all comes down to personal preference and personal economics and, also, as Elbert said, to where you are staying on North Ambergris. If you're staying at, say, Grand Caribe or points south, that would be a different issue than if you're staying at Mata Chica or Portofino or points north.

People with handicaps or physical limitations also may have trouble with some water taxis and docks.

Costal does privates and no waiting. I'm one of those impatient that doesn't want to wait for the bus and all those stops are annoying, so i pay a few more bucks and go now.