Worked for me as well. I simply asked if they would price match to walmart. She said they they don't normally price match but she would credit me $50 back this one time. Actually got more because of Tax.
Because of this thread (and another one which made me decide to cancel pre order at bestbuy) Igot my Red 920 Yesterday and charging plate for $49.99, the associates at the ATT store were more than accommodating. Oh and I am loving this phone, upgraded from Samsung Focus S