I bought a cheap thing off ebay about a year ago, powered by 4 x AA or a AC adapter (available off ebay for £2-3)
Sounds is pretty good for the money, and it fits in my haulier easily enough. Best part is theyre around £10 delivered. Link -
http://www.ebay.co.uk/itm/BLACK-MUSI...item4160e3e6c5