I have an opportunity to purchase a 2004 Allez Pro w/ all Dura Ace for about $1500. Is that a good deal for a 4 year old bike? Bike has virtually never been ridden.

I have the exact same bike and can tell you that I'm very happy with it. A great balance between stiffness and ride quality. I paid around $3k new so if it was really barely ridden it sounds like a fair deal. Just look up the price of 10 spd Dura Ace and the Mavic wheels. If that's the asking price, you can probably get another couple of hundred off.