I started throwing stright at spares quite a while ago, i was maybe 8 or 9 years old. My coach started me with it, and took a while, but once i got the hang of it, i never even had the slightest desire for a spare ball. to be honest, for my own game, it'd be a waste of money. if there were a really cool one out, like the everclear for instance, i'd buy one just for display. lol.
Matt