Having praised the 450 desevedley so I would make the following recomendation.
Go to Hanover Powersports in Whippany NJ and buy a leftover 08 700. They have 3 left that they got from an bankrupted dealer and they are selling them for $8,999 and I get the feeling they will deal even more. Because you live in PA you won't pay sales tax. Don't pay any other fees either. See if you can get one for $8,800 out the door.
The 450 was pretty much identical to the 660 but the 700 is a much better machine with fuel injection, 4 wheel discs, improved air intake, axles, e-brake lever, digital gauge, cooling system, CV guards and lots more. The 450 got none of the improvements..
Good Luck... The 700 is amazing but if you are set on a 450 you won't be disappointed with either.