Pre-built bikes in that priced range are usually not a good value. What looks like sexy bike has a lot of corner cutting to accommodate the price point. Yes it looks great and has a carbon frame but the components are generally going to be low-end to compensate for the more expensive frame material. The least expensive Roubaix for around $1800 is not a good deal, IMO. The other thing is I would really question the long-term quality of a carbon frame at that price-point.

How often do you ride and what kind of riding do you do? That should dictate the type of bike you buy.