For Black Friday, Amazon lowered the price of the Echo, Echo Dot and Amazon Tap, and then they returned to their regular prices after Cyber Week ended. Now, all three products have seen their prices dropped once again, to Black Friday prices. The Amazon Echo is available for $139, down from $179, the Amazon Echo Dot dropped from $49 to $39 and the Amazon Tap from $129 to $89. It's unclear how long these prices will be good for, so you'll want to grab yours before they go back up or go out of stock. At this time, the Amazon Echo is already backordered through til December 17th, but you can still order it, and it should arrive before Christmas still.
The Amazon Echo, Echo Dot and Amazon Tap all have Alexa built in, which is their main selling point. The Echo Dot is their cheapest model, which can be plugged into another speaker. So you can get Alexa built into just about any speaker you want. The Amazon Tap is a portable speaker, which isn't always listening. You'll need to "tap" the speaker to talk to Alexa. Finally, the Amazon Echo is the original Alexa-powered speaker, and has an actual speaker inside, but it's not portable, unfortunately. You can pick up all three from the links below.