its amazingly cheap actually, just about all the ones i linked to have custom electronics that the person themselves built. tiny IR components are cheap! the most costly thing is the time, labor, and frustration in building something that small. after two years of building tiny, the lightest i've ever gotten was 2.8 or 2.9 grams.

planes this size arent gonna hit the market for quite some time i'd imagine. cheap toys like the aero soarer make it tantalizingly close though.

nick