From what I understand, the new Empress Valley Led Zeppelin releases, as well as the Mid Valley Eric Clapton releases still sell well to this day. I guess some "old school" fans still prefer the "official" silver CDs...etc...
I assume that these label are
1) dedicated to hugely popular artist - you can add The Rolling Stones and The Beatles
2) targeted to the japanese market (and US)
3) each release made in very limited quantity
I never succeded to put my hand on one of these very expensive silvers.
Time have changed. But in the history, bootlegging has always been a "rip off story".
There two side of the medals. Some tape have been officialy released after that the record company discovered that there was a market for these recordings. On other matter there was legal issues that prevented the fan to get the stuff (the Beatles)
Even today some bootleg recording are the only access to un-truncated version (Led Zeppelin at the BBC for example) or sometimes the bootleg version can remain superior to the released version (Beatles anthology 3 does feature an erased headphone guitar track line version of "Because" whereas on the bootleg you still can hear it).
On the other hand bootleg label make profit of work made by others.
But honestly who is happy today NOT to be able to listen to any MK 2008 sbd show?
(the closet recordings should we call them).