There seems to be an ongoing theme with smart speakers and music subscriptions these days. Right when Spotify is offering a free Google Home Mini to its paid subscribers, Amazon is running a parallel deal, dropping its entry-level speaker's price to just $1, which it's selling bundled together with an $8 monthly Music subscription.
This promotion technically drops the Echo Dot's price to just $1 but automatically bundles it with an Amazon music subscription. You'll therefore have to pay $9 when placing the order, which corresponds to the speaker's price and the first month's fee. The subscription itself is auto-renewing, but you should be able to cancel it before the first month ends if you're not interested in keeping it, which makes the Echo Dot effectively cost $9.
Unfortunately, just like with the Spotify Home Mini deal, you're getting the older generation speaker, hinting companies are trying to get rid of their stock. Thankfully, you'll be able to pick between Charcoal, Heather Gray, and Sandstone colors to match your Echo Dot to your taste.