First if all what is considered "a reasonably small package"?
The Brahma woofers as suggested by others here are indeed great drivers. I do believe though that they are about two steps beyond what you are looking for here. If you can live with 1.5 cubes then drop a Shiva into that and seal 'er up. Use about 1-1.5 lbs of polyfill in thar and hit her with anywhere from 100-300 watts of RMS power and be happy....VERY HAPPY!!!If you need smaller box, let me know.
Noidster