It's back on "last chance" now... not sure about it, I've had mine for many years, but it might be worth a try to send them a mail and ask!
As for the discussions about favorites... I don't have the Roulette Studio alas, love the Roulette Live a lot, although I find I listen to it all too rarely.
Anyway, the Clef/Verve material is essential in its own way, I feel. The dance sessions are among the very finest NT Basie, and Gus Johnson's drumming is superior (except in showmanship) to Sonny Payne's. But yeah, maybe all in all, the Roulette sessions are a bit more exciting (for instance, "April in Paris" was always more solid, rather than great, in my book), but I wouldn't want to miss the Clef/Verve recordings!