They have done a fabulous job with this museum. Tons of artifacts, displays and interactive content all organized in an intuitive way. Definitely worth a visit!
Fee below is a "recommended donation" of $5. There are additional charges for some of the optional interactive things, like target practice. We spent about 2-3 hours there but didn't have time to do the whole upper level, mostly because I read almost everything in the displays, which slows you down. It would be easy to spent a half-day there if you are a history buff.