NADs is it, I have got a few for £20 -£50 for family.
DS
A&r a60
Between £50 and £90
Hows about one of these for a bit of Mid Fi?http://www.maplin.co.uk/power-amp-1600-220537?c=froogle&u=220537&t=module.
The B grade just £7 over budget but plenty of headroom maybe.