This is just for the raw zooloretto. I think the game could use more money, and what's the point in having the money around in the final stack when you can't do anything with it? Good variant worth knowing about. I will point out that (IIRC), money is a tie breaker in this game, so it's not COMPLETELY worthless to grab $$ in the last round of the game, but it really isn't that appetizing either.
I realize, you can make a truck less appetizing in the final stack with money, but there's way more to this game than making trucks more or less appetizing. So in that vein, after the 15 random pieces have been pulled out of the sack, then the money is thrown-in.
Just slightly spicier without going too far...