Ayup WWD and Jan...
I think you'll find that that compilation is indeed the first 5 of the Christopher Tolkien Books...
I think there were meant to be around 12 or so and i bought the first 5 as first edition hardcovers, then acquired nos 7,8, and 10. I also have the 'Letters of JRRT' too. after the first 5 or 6 from Allen Unwin, they transferred to Harpercollins, and it's there i lost them. Dunno how much they'd cost now... They are indeed 'Literary' books and not story extensions as such, and as such will disappoint most of their purchasers, who will think they're getting more story...
As with Pterry's stories, i'm amazed how Hungry (Capital 'H' notice ) people all seem to be for this GOOD story... they're NOT just for trippy Hippy-types. and I don't mean to offend anyone with that moniker...
We REALLY DO need the Hobbit on Celluloid, 'cos it's the Start of it all, but I need to see Feanor, Hurin, Turin, Fingolfin, Finarfin, Melian, Galadriel, Maglor and MELKOR and Ungoliant too ! plus Sauron in his pre-horrible state too. And i don't think i will in my Lifetime at all... That 'Middle Earth' DVD Boxset really is one for the future and Technology...