unless you know for a fact what kind of geometry you want then drop by a shop to find something. Chances are you'll only be paying a couple hundred more than online, and if it ends up being too much for you, still look around and then try some out, don't look at the prices though and don't tell the employee how much you plan to spend. Try out some bikes and then find the one you like the best, take a mental note of it and then leave.

Look online to find the geometry specs of it and then look around for other bikes with similar frames. If you do not find a MUCH better (>300$ difference) deal then go back to your shop and get that bike. That way you'll have the ability to go to them for repairs and such. I have no worthwhile bike shops around town, have one but I'm getting frustrated with their inventory since it sits for so long without being touched and their tubes and tires are in horrid condition so now i'm back to purchasing online.