VMP does this in nearly all the anthologies now. They rely on you not looking at where else you can buy the albums, or expect people to want to pay a premium to buy all the records in one box instead of buying separately. This one's weirder than most because 6 of the 7 are easily found on Pure Pleasure as AAA releases. I'd bet that Now-Again has the rights only to the unreleased album which is why they got the 2nd billing on the box set again. If you want the unreleased album, you'll likely have to buy this box set (or at least until Now-Again releases a variant of it). I'd have to think that the album will get another release since its so rare, but who knows. We still haven't seen the Zamrock reissues that people claimed Now-Again would release separately.
In this case, it's probably the same price to buy all the albums in it separately from Pure Pleasure if you don't have any and want them all. They are some great albums. I agree with
@serotonein that it's frustrating to pay a premium on a box instead of getting a better price, but all the Anthologies have been that so far. I own two and they are awesome, but they lost me with the Dead box and not sure I'll buy any in the future unless they do a label or artist I love and don't have good copies of their albums.