I've been casually looking for some while, (another spare - spare to fill the garage, lol) although mine are good after refurb.
As Andy says, not cheap, and average about £100, for half decent, that require extra spent for refurb. Factor in new tyre, fitting etc, quite an outlay, but new are ridiculous prices.
I have found them from £65 upwards, but at a low price, they are a mess, and imho really beyond refurb, - corrosion, deep scrapes, gouges.