Not sure yet if it is good or bad that they only accept cash or american express? I think if they took mastercard or visa I would spend a lot more...but sometimes I want a lot more :)
Costco is not always cheaper then places such as target or giant eagle, but it sure does give them a run for there money in categories such as organic lettuce mix, household items, appliances, office supplies, and freezer foods for example.
Costco never has "sales" but they do have coupon books that come out monthly that offer huge sales.
I would also recommend eating at the cafe there, good food, very inexpensive!