So the high value is in what, limited editions and unsealed?
Music collectors, not listeners. Music is to be enjoyed, listened to...no? (...)
Who knows?
Anyway I thing our analysis should not be driven by the crazy speculative prices of unsold items. If you look at sold items you see that a mint set sold in Europe this year around euro 800. I easily see that a Wagner music lover can accept to pay such price for 15 disks.