I know it was a lot more than that when we where there. I checked noonsite and found this:
Cruising
Permit fees: depends on tonnage and the duration of a visit, e.g. a
boat from 5 to 20 tons for a week would pay EC$600 (EC$150 if under 5 tons). The
permit can be obtained on arrival. It also counts as a clearance certificate and with it one need not check out with
customs in order to leave Anguilla.
I don't think you have to pay it if you are there for only one day. We stayed two, one at Crokus Bay and one at Scrub island. I seem to remember it cost $250 for the two days.
If you have 11 days and four couples, your right, it's not a lot of
money. There is a small bay just north of Crokus called Little Bay. You can use
Google Earth to see some pictures. It was very nice. The
coral was medium but the
fish where great. We got surrounded by about a million small bait
fish at one point. You couldn't see anything except the sun and fish.