I'm sorry to hear about your family. Hopefully your dad will respond well to treatment. Is he a veteran? There might be some private organization assistance out there. My dad passed before we really had a chance to look (late diagnosis).

About the Joes, you might send a note to some of the online stores, JoeArmory, GuruPlanet, SmallJoes, etc. and just see if they're open to buying collections. The price probably won't be optimal, but like you said, it won't be a months long sale, either.