Depends on how clean you mean. Can get them for mark 2 Golfs as cheap as £250, bu they will need some bolster repairs, might have f*g burns and will need a good clean! Will be above £400 for a good clean set, with no tears, f*g burns, knackered bolsters etc. Also depends on what trim they will be in!
It's worth spending more, as although there are cheaper ones, around once you work out a new bolster at £32 inc postage, then a trimmers cost of around £40-60, it soon starts putting the price for the cheaper ones to the same or over the ones that need nothing doing to them. Of course if more than one bolster needs doing . . . Also where will you get the new material from if there are holes/tears etc?!
