You know, I'll bet that would work great with an optical mouse if you had some sort of patterned decal around the bottom of the PVC to give the mouse something to look at... and optical USB mice are a lot easier to find than ball USB mice! And without having to keep a ball in place you could remove the mouse shell and mount it more gracefully...
Again, this is just a killer idea! And you could go down to any auto parts store to get a wheel rather than cannibalize arcade wheels....