An Electric Piano is probably your best bet but they mostly start around 320, http://www.gear4music.com/Digital_Pi...ic_Pianos.html . It's probably best to try ebay and buy second hand for that sort of thing because you won't get anything new for that sort of money, the only problem with ebay is that most of the ads say "pickup only" for electric pianos.
http://shop.ebay.co.uk/i.html?LH_Auc...=p3286.c0.m301
Iain.