This looks like a bit of a bargain as it is currently £107 on amazon.
Ministry of Sound Audio M Plus Multi-room Speaker, works via Wifi and BT. 2 year warranty and reviews on amazon seem to be positive.
The speaker is £59.95+postage but may work out cheaper if you purchase more than one speaker
Brand: Ministry of Sound
Type: Audio M Plus Multi-room Speaker
Warranty: 2 years
BT, Wi-Fi, Multi-room connectivity
MP3, Internet radio, music services
Free Ministry of Sound app
Connectivity: IEEE 802.11 b/g/n 2x2 MIMO Wi-Fi, DLNA, All A2DP supported devices, 3.5 mm audio input
Power Source: 4 hours playback, Line In, Internal rechargeable battery
Battery life (from full charge): 4hrs @ 70% volume level, 6hrs @ 50% volume level
Charge time: 2 hrs
In The Box: Power Supply (UK/EU) and cable, User Manual and a Warranty Leaflet
Dimensions: 195 (W) x 284 (H) x 195 (D) mm
Weight: 2200 grams