If it's in your budget, we highly suggest you get a running wheel for your chin. The best running wheels are the Chin Spin (15" only) by Quality Cage Co. and the Silver Surfer by Chinchillas.com. Safe running wheels should be at least 14" in diameter and have a solid running surface. It should be completely open on one side because chins jump on and off when the wheel is turning. There should be no cross bar. You should never use a wheel that has horizontal or spoke type bars as the running surface. Do not use a plastic wheel or disk. The ones sold in pet stores are not large enough and your chin can chew it. Make sure a wheel will fit inside the door of the cage. If you get a Martin's cage, put the wheel in the cage first before you attach the front panel of the cage. You will want to have a shelf above the wheel because they will try to stand on it which of course could cause injury.
The Flying Saucer (galvanized only) is also very popular with many chinchillas, but they are pricey. Do not use the unsafe plastic ones sold in pet stores. The original flying saucer is safe for your chin, but some chins just don't take to them as fast as they do a wheel. I have one chin that has a flying saucer that the previous caretaker donated and he is crazy about it. They are a good option for you to purchase.
Safety Notice - Super Pet Silent Spinner is a very unsafe wheel. There have been many reports of the wheels coming off the bearing. These are very poor quality overall and a safety risk to your chin and a waste of your money. Other unsafe running wheels are: Comfort Wheel by Super Pet and Run-A Rounds Exericse Wheel which should never be given to your chin.
Safety Notice - Run-about Ball (by Super Pet) Do not use this product ever! I call it the 'Torture Ball', but many in the chinchilla community call it the 'Death Ball'. Get the picture? These balls do not allow air flow (despite the slits) and your chin can easily overheat. They are very unsafe for your chin. Your chin also poops and pees in them which means that is getting tossed around as he is moving around. The chin also has no control when in one of these and can bang into furniture or fall down stairs. For those of you who have one of these and think your chin likes it, well -- he doesn't, he is trying to escape from it. Throw it away and find a better and safer way for your chin to get exercise. This is another product that should be taken off the market.