I just purchased an 07' Allez Comp for $1100, so I think you may be able to get an '06 Allez Comp for a bit cheaper. It certainly couldn't hurt to ask for a better deal.
As far as fit - I agree that the 52 is the right size for you. I'm 5'9" with a 30" inseam and my Allez Comp is a 54" and fits like a glove, so I would think the 52 is perfect for you at 5'6".