So you're looking for a recurve or longbow, correct? I generally buy most of my items from a local archery shop. For one to support the small guys, and the most important reason is I couldn't shell out a grand for a bow that I haven't got to "try out." I am a big advocate of buying things online, but I wouldn't advise purchasing a bow online - at least not without trying it out at an archery shop beforehand.
The bow pictured I actually purchased from a shop online after I shot one identical to it (as well as a few other models) at the local shop. For the more "generic" supplies, I would have to suggest Ebay just due to the fact that you can always find good deals on stuff. Lots of people have good things to say about Lancaster Archery and Hunter's Friend on one of the archery boards I read.
The best advice I can give you is to shoot a lot of bows before you buy them. There's really a lot of difference in different brands and different models within the same brand. However, I haven't shot a long-bow in a loooong time, so I can't be much help to you there. I am glad you are taking it up - it will be a fun way to spend time with your son. If you have any more specific questions, I will be happy to try and help.