I don't know about the Costco website, but I can personally attest that they're one of the most customer oriented companies I've ever dealt with. They shave dollars off their prices in a lot of creative ways, but NOT by skimping on customer service, except that on weekends the lines at the customer service desks can get a bit long. But for what you're saving, it's well worth it.
BTW, you can also get a free American Express rebate card with your Costco membership. Last year, on top of the incredible prices I got at Costco, by charging everything on my AmExp card I got an additional $76 rebate.
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Price is a crazy and incalculable thing, while Value is an intrinsic and indestructible thing. G.K. Chesterton