30% off of MSRP is a must for me. I do the research. Trailer Mfgr.- floorplan- construction materials etc.. When I've decided on a make & model then I start the negotiations. Each time we've bought new it was easy to determine the MSRP. The dealers would quote me via email and they just filled out the factory buy sheet (Retail Price List with options listed) and sent it to me in pdf format. I in turn printed it out for future reference. Be polite and indicate you're very interested in buying soon.
Each time I get in verbal (phone) contact directly with the dealer(s) and manufacturer. I've found out information that the dealers didn't know about even.
Just yesterday I received a low bid on a 2014 Keystone Cougar High Country 321RES Trailer so I bought it. Build is scheduled for 4/16/2013 and I should have it a week later.
Distance can be a factor in your final decision. I certainly wouldn't go with a dealer a 1000 miles away just to save a $1000.
Happy trails,