.44 Spl. ammo
... or buy a basic reloading outfit, .44 Spl. brass, bullets and roll your own. One hell of a lot cheaper than factory ammo. However, since you aren't already reloading, and if money is no problem, by all means, stock up.
What's the point in shooting a gun with ammo that makes a cash register 'Ding!' instead of going "Bang!"?