I've used Virgin Island Sailing for our 3 charters. The primary benefit is that I just give them our boat parameters and budget and they provide a few options of boats that are still available. The cost for the broker is paid by the selected company and I don't know of any companies that will reduce their price if you don't use a broker. VISailing also provides the latest cruising guide and an online cruising guide. Also remember that no all companies allow brokers, so after you get a list of options, you may want to check companies that don't pay brokers.

If you know exactly what boat you want and/or you know who you want to charter from, then it's only a matter of whether the broker provides you with other services/products that matter to you.

As far as waiting to book in low season, it's a matter of whether you're particular in the boat requirements. Obviously, the longer you wait, the fewer boat options you have, but possibly a better price. As mentioned, there are already some pretty good deals during low season which may not adjust your price much. Since most boats are owned by someone other than the charter company, the company has to pay the owner an amount and then the company has to make some money. There's always a limit to their bottom price. If you show up at the office and ask to charter any boat they have ready, I don't think you'll get much more of a discount than booking earlier. I'm only going by the emails I receive from the charter companies and VISailing on their specials for late selection chartering.