Im thinking they did the major over haul in 2006 , but, there is always a chance that a couple of 2005.5's are out there - If you like that motor, you shouldnt ride the 06+ unless your willing to buy on right then !
Did some looking and according to KBB , retail for a 2005 Factory R is 10320 - -
BTW, is this the for sure real factory ? Seems like they did a model that was trak only in that time frame, no lights or anything, if thats what this is, yo uneed to get it. those are killer ! There was a guy at a trakday I did @ VIR that was turning 1:32 around the north course - thats smoking !