If you know what your looking for, and you can determine if your buying someones burdon or not, then yes, take a look at used bows for a good value. If you cannot tell, then a new bow with a solid warranty is right up your ally.
If your younger and have some growing yet to do, make sure if you buy a bow, either new or used its capable of growing with you, and your future needs. Keep in mind, on average people move on to other bows every 3-5 years. Some bows, you have to buy new cams to make them fit you, and that can be very costly. However the bow makers have seen this market trend and are adjusting to bows that can cover you from nearly cradle to grave. This is truly an exciting time to be an archer, the choices are unlimited.
Good luck, and if you need any tips..throw me a PM. I can also arrange for you to shoot the Razor, and Apprentice.