I think that this is the weekend for the horse expo show in Harrisburg. That would be a good place to see what the dealers are willing to give on new plus you can kick the tires on a lot of trailers.
If you know what you want, spend some time researching the sites. Horsetrailerworld for one lists the "hits". A lot of hits along and the trailer not moving means too much money, a bad design, or perhaps mechanical problems.
The market is glutted with horses and trailers. Unless you are a super nice person with lots of cash, take advantage of it.