Work lamps?

Hello,

My lathe came with a small work lamp on it which has burnt out at some
point. The problem is I'm not having much luck finding new bulbs for it.
Halogen lights are meant to be better but there's only so much I can afford
and £25 - 50 for a light isn't an option right now. The light uses quite
standard looking bulbs. They're small (About 1cm across) standard bulb shape
ones with a bayonet connection at the base. The glass of the bulb appears to
be silvered all over on the inside (Any ideas why?) and the base has 12V 5W
imprinted on it.

I understand what that means but do any of you guys know of somewhere on
the net that sells bulbs similar to this for lighting work?

Thanks
John