with that budget you really can't go wrong anywhere. An heirloom type gun can be anything. It could be a WWII GI 1911 that someone's grandfather used to help liberate France or a custom engraved masterpiece.
But my suggestion would be to find a very nice (i.e. Wilson, Les Baer, Ed Brown) 1911 and then have a master engraver work the entire thing over from stem to stern with gorgeous detail all over. A hand-made 1911 with hand-worked engraving would be a sight to behold. Find yourself some super rare grips made from a fine wood, like Koa, to top it off and you'll have a unique piece fit for a magazine cover.
Imagine having a gun made and having an artical done on it in Handgunner or something like that and handing both down the pistol and magazine spread to your kids. Very impressive, indeed.