pet planet is another good stocker
Even though it seems like it on here sometimes, there are tons of other options! Its just that most of us like the wodent wheel
Other options include: the 12" silent spinner (it doesn't come in 8"), Karlie wonderwheel, wodent wheel lookalike (can be found on zooplus) and any basic wheel that is 8 " or above.
Another thing to mention is if you get a paricularly long haired syrian, certain wheel aren't suitable cause of the spindle. The long hair will wrap around the spindle.