Regarding those $500 7740 sets: I believe those were bogus auctions. There was never any feedback recorded for either one, and I was one of the bidders. I received an email from ebay stating that my bids had been cancelled by ebay because someone had created false listings.
I am eagerly awaiting the new Lego train sets, too. But I think the sets we are looking at are considered "play train". I believe that TLC is still making the final preparations for a line called "hobby train", which will be a more advanced type of set. Hopefully this will continue the 9V scheme of things. We should know by the end of the summer, I hope. :-)