Ebay is a good place if you don't have a local pro shop. A local shop allows you to take him in and try on some bindings. I have worn Transits over the years and I love them, a bigger pair of them would work well. I am wearing closed toe Murrays this year and they are nice and comfy. Some people say they give you better board control with closed toe, I have noticed a subtle difference in this area.
I think that in last two years, bindings have been much improved in comfort and I think you would be ok with most of the upper level bindings from 06 and up. In my experience binding manufacturers size recommendations run close to street shoe size and I have worn Hyperlite, CWB and Liquid Force. I think that you should ask your son about his preferences about binding stiffness and post those up and then people can make better recommendations. Also, after you find a price range, that can help with recommendations.