The project we started 30 months ago finally reached its main objectives. Mainly, get the cheapest, simplest hovering thing to fly itself. Ended up with a persistence of vision attachment on it. Also wanted a camera, but the camera is a long way off. It ended up using ground based machine vision for navigation.
Getting smaller than this would actually increase the price. Sure, there are chinese toys which sort of hover themselves but can't control their position, like the Vectron Wave UFO, but Marcy 1 is the 1st thing which can control its position.