Not sure where you are located, but summer camps are great for science education. It isn't a long term solution, but it will give him a taste and way to try out many different things. I'm probably spoiled in what is available in my area (SF Bay Area), but their are tons of science related camps. There is one that we went to last year that was great and (assuming you are in the US) is a franchise called Engineering for Kids. They also do afterschool programs.
I second the LEGO League. I became a coach since there wasn't a local team. It's a Jr team though since my son is only 6, but it has been really fun to teach the process of creating and wrapping physics, engineering, and natural sciences into it. It's also great for team building and social skills. Check out LEGO Mindstorms for an intro to robotics.
My son is also interested in chemistry, so we plan on buying a home chemistry set. I bought my 3yo daughter a play lab set for preschoolers with beakers and experiments and that got them both hooked even though it was mostly food coloring and baking soda. The chemistry sets run the gamut and just buy him one that is for a much older age to get started.
Search for Exploratorium as they have some books and they are a fantastic museum. I find that books are immensely helpful when they are written for home experiments. There are lab supplies available online.
Good luck and enjoy learning along with him!
