not sure of a number on a 2010 21se.
general points to consider though when buying a new Parker.
Yamaha has new engines out there that offer significant improvements over the previous generation. do you want to buy a boat with an older generation engine which will affect resale value?
Parker makes very few if any changes from year to year on their hulls so the model year really isn't a big deal.
you are buying a leftover model which means you can purchase outside of your dealer territory. this means you can negotiate a great price and get a good discount depending on how motivated the dealer is, and how far you are willing to travel. i always buy the leftover model. on 23 ft DVs i have seen discounts from $5-$10K.
and yes, you can get your boat serviced from any Parker dealer. I personally have never needed service for anything other than the engine. so, i take mine to a nearby (nonParker) Yamaha certified dealer for warranty issues.
good luck