Just got off the phone with an Amex CSR and here's what I found out after playing "what if" with him:
Me: Suppose I bought a monitor locally for $400, and then found the monitor online for $350 + $70 shipping, for a total of $420. Would I get a $50 refund?
Him: Yes, we don't consider shipping when pricematching.
Me: Suppose I bought a monitor online for $350 + $50 shipping, for a total of $400, and then found the monitor locally for $350. Would I get a $50 refund?
Him: No, because we compare just the prices for pricematching, and don't take into account shipping or taxes.
Me: How do you know how much I paid for shipping? Does it appear as a separate charge on the card?
Him: In order to receive a pricematch, you have to send in your invoice (which shows how much you paid for shipping) along with proof of the lower price, which can be anything from a magazine ad to a printout of a web page.
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So...I can't pricematch Sam's against themselves and nix the $220 shipping charge. But, the converse will work. If I can get the monitor somewhere else, I can pricematch Sam's $300 price and receive up to a $250 refund.
After a pricematch, I think that any rebates you got would still work, since those would not appear on your invoice. I forgot to bring that up before, but I'm done talking to CSR's for a while...if someone wants to confirm this that would be great.