Welcome to the forum. Not that it really matters but you might want to be sure you're actually getting a Classic. These days you see a few R3s being sold as Classics when in fact they're not. The engine's the same but there are some significant differences between a Classic and a Standard. The Classics were all 2 tone for a start, and Standards were a single colour. Classics also had low-set floor boards and pull back handle bars, a dual touring seat instead of a tandem and cone shaped exhaust tips. Of course a lot of these features have been added to Standards - eg I did the seat - or changed on Classics, so the real give away is probably the paint (look for the initials of the person who hand painted the gold pin stripe).
Personally I prefer the Standard because it has pegs and flatter bars, and mostly because it's what I have. Others prefer Classics. Either way, the '06 is a good model with many of the bugs of the "first edition" Rockets ironed out. I have over 65,000 trouble free km on my '09, which is not only more than I've ever put on a bike, it's more than I've ever put on a car in over 40 years of riding/driving. With only 14,000 miles on the one you're looking at you should go for it.