If your Cocker is ball obsessed, can I offer some words of caution about ball launchers - don't use them on every walk, and don't over-use them - it was one of the things that seriously led to Honey's utter obsession with tennis balls (to the point of guarding them, digging them up on walks when she's sniffed them out from 6 inches of mud, refusing to return them, shredding them, stealing them from other dogs, burying them in the garden and bouncing up and down beside us if she could smell one on one of us...)
They're great things if used carefully, and most dogs love them, but if your pup has already proven to be fairly ball obsessed do be careful not to unleash a beast...