How much of a discount you get is also dependent on how long the tt has been sitting on the lot. The biggest discounts are on last years models, the smallest discount is on special orders. The rest of the trailers fall somewhere in between. The discount will also depend on the popularity of the brand/model, whether or not it has slides and other features, and how popular those features are in the local area.
We got a great deal on a Jayco 22FB in April. It had no slides, no bunkhouse, and the dealer had three of them (more than 30% off). There are other Jayco dealers in the area.
In January we got a pretty good deal on a Sprinter 27RLSS. He wouldn't come down as much %-wise but threw in some free things (extra battery, vent covers). The Sprinter has a slide but no bunkhouse (both popular items here) and is heavy for its size (unpopular here in the land of SUV). There are no other Sprinter dealers in the area.
If you want to buy a trailer cheap, look for ones that have been sitting on the lot for a while. When you start seeing the 2014s on the lot, you will see the price go down for the 2013s, sometimes significantly. Buy a brand that has competition in the local area.
We spent four months looking for our second trailer, browsing prices on line and visiting over a dozen dealers up to 250 miles away. Some salespeople were great, giving us the tips above; some salespeople not so great. Personally, I wouldn't buy any distance away that I am not willing to drive to at least once or twice. We got lucky on both our tt purchases in that both dealers are less than 20 miles away. Both tts went back to the dealer twice, each one once for warranty work and once for add ons.