DGG has reissued the first set. Hope no one here paid premium OOP prices for it. Amazon has it for $160 now, but yesterday it was $130.
As I write this, the second set is on sale at Amazon for $111. I'd grab it at that price if you want it. I did, even though it's a bit heavy on the vocal/opera for my taste. Last week, it was $150-someting on Amazon. Last week J&R had it for $121 but this week their price is back up.
The big online retailers use automated models to adjust prices from day to day. Based on what, I don't know.
There's also a similar box set celebrating the Living Stereo's out there. I have most of it already in one format or another, but I'd think it'd be pretty desireable for someone starting to build a classical collection.
Another FYI on this subject: Amazon's been running a big discount on the Horowitz Complete Original Jacket Collection. However, I'm saving my money for the forthcoming Heifetz set.