Cheap Add On Speakers for anyone with Play-Fi devices, like the Klipsch Powergate or Paradigm PW/Link PW/Amp. Pioneer Elite F4 Smart speakers are avaliable on eBay for $59 new. No link because I am not familiar with the seller, so search Pioneer F4 on eBay...but others are close to this price.
The F4 originally sold for $200-250 and sounds quite good I think (a LOT better than an Echo, similar to Sonos Play One). It has a mic built in and a lot of, but not all Alexa functionality.** One nice feature is that you can broadcast anything you plug into the Aux Input to other Play-Fi devices. The Powergate does this, but the PW/Link Amps do not.
**For example, your can voice control almost all Alexa smart home devices...but you cannot "broadcast messages" like you can on the real thing. If you start a Spotify stream from Android, you can control play/pause/skip by voice through the F4, but you cannot start a Spotify stream by voice.