Help reg. cheap WiFi speakers (for Spotify)

I want to get my mother in law some WiFi speakers, as I've got a Spotify Premium account (free through my Spark mobile subscription).

Nothing expensive (under $100) as she's certainly no audio geek.

Would something like the Kaiser Baas Sound Shift be an OK buy?http://www.trademe.co.nz/electronics-photography/home-audio/other/auction-1079731220.htm

She's got an old stereo (probably 20 years old or more). I assume Kaiser Baas Sound Shift would work with this.

Or would the Pioneer XW-BTS1 be a better choice?http://pricespy.co.nz/product.php?p=1599166

Or finally, the LG Music Flow H3?https://shop.jbhifi.co.nz/ipod-mp3-portables/wireless-audio/lg-music-flow-h3-wi-fi-multi-room-speaker/91287

She would control the music through her Samsung Galaxy tablet and I don't want to buy her a speaker, which only can run on batteries. It has to be plugged into a power socket.

She basically has to be able to stream music from Spotify and also TuneIn radio (or similar).

One more thing: The router is downstairs, but we would like the speaker to be upstairs.We've got a Sonos Play 5 ourselves and it's worked fine with having a Sonos Bridge next to the router and then the Sonos speaker elsewhere in the house.Can something similar be achieved with a cheap WiFi speaker?