I made the personally made the switch from Losi to associated this year and i absolutely love the B4, T4, and B44. great cars and very nice performance. Get yourself a decent charger so you don't have to upgrade it in the near future. Ice, Hyperion, even the ofna digipeak are all good options. I would personally start off with Lipo and Brushless, do your research on Lipo's and make sure you understand caring/charging them. Brushless is pretty simple to set up and for that i like either the lrp or novak. I prefer to run sensored motors versus non-sensored stuff, personal preference. Batteries, well i am sure most people know i will say Trakpower but orion's are also good, maxamps are ok but prices have gone up. Team checkpoints are made by trakpower so they are the same just different color.
Take a few weeks and look around at local hobby shops and at your local track and see what the others are running and what your local shop carries parts for. Good luck and enjoy the time with your son.
Bulldawg R/C Batteries and Products
Nimh and Lipo Batteries and accessories
Team Driver for: Proline, Team Epic/Trinity, Hex Crew, Bulldawg R/C, Speed Demon Hobbies ~~~~TEAM CRUNCHY~~~~