Okay, so how come there's no Chan on DVD? This is a golden opportunity, and you're blowing it! With all the great serials out there, surely there's a place for Charlie Chan. Anybody with me? Also, more classic Sherlock Holmes wouldn't hurt.
MGM released a pretty big Charlie Chan box set on laserdisc in the mid-90's, which would lead me to believe that the rights are now owned by Warners. Good luck in trying to get them to put them out.
Marengo and Roan are basically public domain outfits, so if any of the Chan films have fallen into PD, they'd probably do them if they could get their hands on prints/video masters.