Retailers are obligated to honour advertised prices. There was a Dell ad in a newspaper with an error in the price for a laptop that I was able to make them honour about 10 years ago. Keep your invoice once you get it. Here's a snippet from mine:

Delivery Information for #: 863151101 | Order Date: November 18, 2014

Shipped ItemsEst. ArrivalQtyItem PriceTotal PriceTax Code
UPC: 0088411609164
Thu 11/20/20141
$259.97
$259.97J
Regulatory Fees
  • Tv's 19-30" env fee for Dell 27 2560 x 1440 LED IPS Monitor
    		• 1$12.25$12.25J

    Shipment Summary

    Items Subtotal:$259.97
    :$12.25
    :$35.39
    Shipment Total:CA $307.61


    Joe Murray, PhD
    President, JMA Consulting
    joe.murray@jmaconsulting.biz
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    416.466.1281