Bloomingdale's has Amazon Echo Dot on sale for $29.99.
Text "Bloomies" to 25666 to receive a unique 20% off coupon, making this item $23.99 before tax.
If you have the Amex offer of "Spend $150 or more at Bloomingdale's, get $30 cash back", then you can make this deal sweeter by purchasing six (6) or more to trigger the credit, depending on your tax situation.
Note that the item is expected to ship within 19 days, so it may or may not arrive on time for Xmas Eve.
Additionally, Bloomingdale's has the Amazon Echo on sale for $99.99.
You can use the above coupon code for an additional 20% off to get it down to $79.99, plus possibly more savings by using the Amex offer by purchasing Echos.