Well, without reference to a budget but presuming that £169 per room for Sonos Play:1's it too much, and presuming that your family would be none too impressed with a bunch of cobbled together components in some kind of Heath Robinson solution, then the next logical choice would be three Pure Jongo T2's at £80 per room. I mean it has to be a wireless speaker/receiver/player all-in-one just to keep the costs down.
Pure Jongo is cheap. But compared to Sonos you're sacrificing a lot of creature comforts that I think would make the Pure solution quite irritating after a while. For example, there's no support for playing your own music from PC or NAS; no Apple Lossless support, you can't access Spotify or any other 3rd party streaming services directly from the device but have to subscribe to the Jongo library instead. You can stream from a phone or tablet using Bluetooth, so you can access Spotify etc that way but Bluetooth only works to one speaker at a time which means you can't use the phone/tablet as a music source and have multiroom. There's also reports of gaps between tracks as the controller app sorts itself out in playlists. Speaking of which, you can't mix 'n' match sources in playlists. On the plus side though you do get a Line Input and a USB input. I'm not sure what they support or whether you can use them to port music to other Jongos in your multiroom setup though.
Sonos might be more money, but most of the above are not issues with their players. There's a broad range of file format support. Streaming direct from phones/tablets is there so you don't really need a dock. Sonos has very wide support for 3rd party streaming libraries and there's no issue streaming music from phone/tablet/NAS/PC/online to one/some/all speakers in any combination you wish. Sonos doesn't have it all its own way though. There's no physical line inputs and file support doesn't extend to high resolution audio files such as 24/96 or 24/192. There is support though for FLAC. Finally, you'll need either a direct Ethernet connection from one of the speakers to the house router or to purchase the £40 wireless bridge if cabling is not convenient. Oh, and it's more money. Personally though, I haven't any customers who have purchased Sonos and regretted it, even when it has been a bit of a stretch financially. They forget about that once they find out how easy the system is to use and live with. For what it does, it's unrivalled IMO, and worth the extra compared to any other multiroom system.