That's pretty much what I do, Jane, and my Options are so awesome for Magic Loop that I don't need 2 circs at all anymore.
You can also pick up some "extras" for the Boye interchangeables set***; my Hobby Lobby stocks them, and no one piece costs over $2.99. They sell needle tips in most sizes, cables in 3 lengths, and an accessories pack that includes 2 end buttons and 2 cable-joiners. If I didn't have time to wait for a Knitpicks order (shipments from them take a while to get to me), that's what I'd use.
It's an especially good idea to pick up some when they put all knitting needles on for half off, which is usually once every 2-3 months. If you don't have a Hobby Lobby near you, they sell online at: www.craftsetc.com.
***You don't have to own a set to use them; everything you need comes with.