Gosh, in 2010 you updated your profile to indicate you are shopping for a trailer for you and your wife. It is now 9 years later. You sure are hard to please! LOL!
Just poking fun.
To answer your question, dealers often use borrowed money to pay for their inventory, which is called a floor plan. Once a unit is shipped, almost always, the dealer has to pay for the unit, so it is then "floor planned" or put in his inventory. Once the buyer's financing is sold to a lending institution, or the buyer pays cash, the floor plan is paid off, and any difference between the floor plan pay off and the amount the dealer collected for the sale of the trailer is gross profit. Subtracted from that gross profit is sales commissions, costs to prepare the trailer for sale, any give aways such as battery or starter kits, and overhead costs such as insurance, electricity, support personnel salaries, property taxes, etc. The result is the net profit which may be surprisingly small.
Therefore, expect little to no difference in pricing from an ordered unit to a unit purchased from inventory.