Cage price is about average. Accessories seem a little steep unless it comes with a proper chinchilla exercise wheel. Here's all you need (prices in estimated USD):
Shelving and hardware $50.00
Water bottle $10.00
Wood chews, pumice, etc. $20.00
Chin chiller $10.00
Dust bath - $10.00 blue cloud chinchilla dust
Dust bath bin, preferably metal, although a thick glass jar can be used - $0 to $15.00
(around $120.00 new. Do not recommend getting used)
Optional:
Metal wheel 14" or larger - $100.00 (Also see kageri's notes below. I use a silver surfer myself but feel chins much larger than 500g would be better off with a 15")
Metal retrofit tray for FN cages - $50.00 (although guessing here) sometimes necessary.
Other expenses:
Pine bedding $15.00, though larger bags may go closer to $25.00
Loose hay $20.00 for large bag - essential part of chinchilla's diet --not an option--
Pelleted diet, 5lb, $15.00 (never the kind with treats or fruit mixed in. Never give chinchillas nuts) Don't always assume that mixes sold for chinchillas are appropriate for chinchillas.
Optional items that you will be wanting soon:
Sealable container for pellets and bin for your hay, broom and dustpan (one by the cage and another set for where you dust), shop vac with large diameter hose (for loose hay), mat for under the cage. Also a thermometer is essential to monitor room temperature. I recommend the kind that tells you high and low temperatures. Reset it each day and see how hot it actually gets in the room near the cage, preferably, before you buy a chinchilla. ($15.00)
A gram scale is highly recommended (weigh your chins once a week, keep logs, and avoid headaches if you should encounter illness) ($20.00)
Don't forget a suitable travel cage as well.
Make sure the room temperature will not exceed 75 degrees F. You may consider a window or freestanding air conditioner if you live in a warmer climate. Otherwise you are at a high risk of death from heat related illnesses.