No, they've been out-of-print for 10 years. I collected my set 6-7 years ago off eBay. At one point book 12 was going for £120 - glad I walked into a second-hand bookseller the same week and got it for £1.20 They're worth getting if you can find them, I expect they're not that price anymore and the first ones tend to go for under a fiver. There's a list of them on Wikipedia.

They really do enahnce the LW universe, they're very well written and add in much more than the gamebooks.