My wife and I were married on Po'olenalena Beach back in 2010 by Rev. Ron Lowery, the former "Maui Marrying Man", and couldn't have been happier with everything. Ron retired a while back, and I don't know anything about the person who replaced him.
That said, there are two things I'd personally be on the lookout for - locations (have a backup), and time of day. Our ceremony started at 9am, and even by then it was getting scorching hot (mid-September). The beach was actually empty that year, but when we returned the very next year at the same time of day, it was packed.
I also wouldn't worry about the fees. They are minimal at best, and any good local company will be able to handle the beach permit on your behalf. The only thing you should really be responsible for is obtaining the marriage license, which took about 20 minutes for us.