First, find a shop that caters to roadies. Second, find a salesperson and tell them up front what your budget is and what you plan to do with the bike, ie: "I have $800 to spend on a bike for club rides." Most likely, you'll get some questions about what components you'd like (Campy/Shimano, Compact/Standard/Triple, etc.), and then be on a test ride.
If you get any static, say thank you and move on. Eventually you'll find a shop that will want to help you find the right bike.
By the way, plan on spending extra on bottles, cages, and tools. You'll not only need them, but you'll also make the shop owner happy.