DO NOT EVER BUY NEW for your first ever trailer. Remember, what ever you pay for it will depreciate 30% as soon as you pull it off the lot.
Looking at and finding floor plans you feel you can live with is important. But most people will find faults with their first, second, heck maybe even their third or fourth trailers and will wind up selling and moving on to something elso within a couple of years. So there is no reason, unless your made of money and like throwing it away to buy new the first few purchases.
FR, and Keystone both make a wide variety of trailers in all sorts of prices. Some good, others meerly OK.