Pull up the Batavia dealer's site I referenced above and see if they have the trailer you're interested in and what they are selling it for. Then you have an idea of where to start your negotiations.
If they don't have your trailer, do a Google search and try to find one that's advertised by some other dealer.
The internet can be your friend in this situation.
And maybe consider traveling if you can find a really good deal.
These trailers depreciate much much faster then cars/trucks. You must absolutely buy it at as low of a price as possible or you will be in deep trouble when the time comes to sell it or trade it in.