This is on the expensive side, but still less expensive (and less painful) than declawing the cat:
Blomus 68592 - Tarro Wall-Mounted Toilet Paper Dispenser
From the review on that holder: "I love this because it covers the toilet paper.
This product is great if you have kids or cats to keep them from playing with the toilet paper."
p.s. many cats resort to peeing in random places after being declawed (a friend of mine had a cat wouldn't use the litterbox for months after being declawed) so you might just create more problems if you go that route.