erm, no to £50, i think a chromed tin one for £50 would be fair, but a great condition alloy one you can use a charge carrier pipe over is worth far more
as for polishing it up, it was a mess when i got it, but spent hours with wet and dry coarse to fine and autosol.
it's a graft i'm afraid, but well worth the hard work as it's hard to find a tidy one if you can find one at all these days.