Depends on general condition and whether they have original GEC/Osram/Marconi KT66's I think. They'll get top dollar if all original or have had recent Quad service. I get the impression that non-quad services almost make them less desirable than completely unserviced - makes little sense to me but there you go. For instance I had a pair of functionally perfect Quad II's that had been serviced and resprayed with new set of Sovtek KT66's that I sold on ebay - went for about £400. I then sold a completely original but untested very tired and flakey looking single Quad II with original but possibly knackered Osram KT66's that I sold on ebay with an entirely honest description for £330!?
IME guide price £450-£900 on ebay, depending on who/how many bidding.
Not sure about the 22 though, good to complete a set but not sure how many people still actually use them?