In the past, I have hand drawn all of the mountains individually, which is needless to say a huge time sink(as well as arm/hand cramps). One issue I have had was getting a consistent look from multiple mapping sessions, so that's a down side.
As for brushes, I think several hundred is way to many. NOT counting pre-grouped ones(which might total more than the individuals to account for lots of combos and shape), I would say a dozen or two, perhaps three tops(this is just for standard mountains, not counting mesas or volcano type land forms). Once you get past a certain point, many people just get information overload and having to many choices makes it hard to pick and thus they just stick with only a few anyway. Another option might be to break them up into groups, so those that want all can just grab them and those that don't can just get the group they like best.
I do have to say I admine your persistance though, so here... have some rep.