Hey, Bang...my girlfriend, AmandaL here on the board, lives in Melbourne and we collect mangroves from Sebastian Inlet year round, just about.
Last year, I collected over 400 Nassarius Snails, 10 large hermits and 10 Mangroves, in the course of a few hours.
Let me talk to her, see if she has time and if so, I'll pass along her email address to you. You guys can get in contact and get things worked out.
If she doesn't have time, I'll be down there in 2 weeks or so and would gladly collect for you, while I'm out doing my own.