There are a multitude of bikes out there. All kinds of price ranges, from the hundreds well into the thousands up to a past 10K! Before buying any kind of a bike go to a good bike shop and talk to someone who knows bikes! Wear something that you could take a spin on too. If they wont let you, leave and go somewhere that they will. REI is a good place, but they only have their bikes and Cannondales.
I would suggest that you buy a bike that will last. Probably a little better than you think you will need for a while. Otherwise you end up trying to upgrade it before its a year old.
A used bike is another good outlet. Join a bike club and ask around. Someone is always upgrading to a different bike.