Mine is a solution provided by the military, but I love them.
BTW, not trying to advertise so kill this if I am violating anything
Helmet with ear cups for standard sound iso.
CEP's (
www.cep-usa.com) for in ear sound.
Mic on helmet.
I have met the CEP guys, small USA company, hand made in AL. About $100 for the set and it comes with the connection components, so you could add them to just about whatever set up you come up with. Might be a bit cheaper with good sound than what you are looking at. We use disposable foamy tips (good for about a month for me flying about 4 hours a day). You can get custom ear molds made for them also for a bit more $.
The sound iso is great with the in-ear PLUS ear cups...but I think you are going for smaller/lighter. I think you could try these ear parts for about $100 and the cords just hang out of ruer ears. Then you just come up with whatever mic you were already thinking about...or just go old school and use a hand mic!
The double deadening these provide in helicopters is so good, its bad. We can't afford to provide them to each new student, so all instructors have them and students don't...radios are either deafening for me or too quiet for them?!?!