Welcome back to the show! Since your son is same age as my daughter, I'm assuming you're under 40. Not enough of us mid-lifers around!
Don't discount hobby lobby, or anyplace else that sells balsa. Get you a small digital scale, and bookmark this link on your phone:
http://www.nclra.org/Programs/BalsaDensity.php About once a month, I go to all the Hobby Lobby's, Michael's, and HobbyTown's in my area (I'm in Colorado Springs) and go through their wood, and typically head home with a pretty good stack of 5-7lb sheets and blocks. It's a bit time-intensive, but do it once a month or so and over time, you will build up a pretty good stock that is way cheaper than paying the prices and shipping of any of the online sources. I still order through National Balsa if I need a bunch of wood now, but collecting wood helps a lot. This all of course predicates on the need for contest-grade balsa, as I do for CL and FF models. If you're just trying to get flying again, super light wood isn't a necessity, and a lot of what those craft places carry will do fine for your purposes. They also typically carry essential tools such as exacto knives and blades, glue, adhesive, ect..
If you're wanting to initially stick with 1/2A, my recommendation is the Sig 1/2A Skyray. I could probably retire if I had a dollar for every one of those I've had in my life. Its a sheet wing that quick to build and easy to repair. Best advise is to get a kit and copy the parts to templates. This way, you can build several without needing to buy a new kit each time. I believe both Sig and Brodak carry kits. They also carry fuel, lines, and everything else you need.
If you want to bump up to bigger models, my pics are the Sig Akromaster (15-19 size) and Sig twister (a good 25 will fly it, 35-40 preferred). Same concept, make templates of the parts so that WHEN you crash it (because that's part of the game), you can build another one. Both of these models are quick builds and will fly well as long as they are built correctly. Both models will also get you started on aerobatics, if that is the route that you chose.
For your kiddo, I recommend the Carl Goldberg "Lil Wizzard" that brodak carries. It's big advantage is the rubber band mounted engine. He's going to be hitting the ground quite a bit (again, we've all been there) and that engine mount design will significantly reduce the chances of the nose snapping off in a crash.
link up with a local club in the area. Lots of friendly, experienced people out there to help you along, and its just more fun to get out and fly with other folks. Find out when and where local contests are happening, go and spectate. Contests are fun, and the social aspect has become more and more important to me as I get older.
The newest and greatest help is this forum. Using the search option, you can pretty much find out anything about anything. However it can be a bit finicky, so if all else fails, post your question and we would be happy to help.
The most important part....have fun flying with your kid! I started when I was a bit younger than him, and all the models mentioned were part of my progression and many others. Countless, priceless memories of going to contests with my dad (who is also on this forum) throughout my childhood, as I'm sure you have from flying with your dad. Best of luck!
Cheers,
Sean McEntee