To buy your first bow you really need to have someone with you who knows about bows, or a trusted shop. Assuming you don't know much about them.

Bows have to "fit" you. If it doesn't you will never shoot it well. Some shops are GREAT, some are terrible.

Buying used online is a great way to find deals, however you have to know what you are doing to make sure the bow will fit you or can be adjusted to fit you.

I'd say talk to a good shop in your area. Be honest, tell them you want a good/used bow, but will buy all the accessories from them. They should help you.