Good places to buy:
BHphotovideo:
Good and reliable. A lot of choices.
Buydig.com or Beachcamera.com (same company):
Good prices and reliable but not many choices. Nikon authorized dealers.
Adorama:
Good selection but average prices.
Ritz Camera:
Good selection but higher prices.
Amazon.com
...
Stay away from the other dirt cheap online stores. They reap you off.