Discogs prices don't always reflect the reality. It's place of opportunist sellers. Everything has its price, and even if item would be part of your collection you have no intentions to sell, if someone is ready to pay XXX USD, I'm sure deal is made. I'm sure this is the tactic of many noise sellers in Discogs. And suddenly you have situation where some relatively rare item, everybody puts price tag from 150 to 500USD, with no intention to sell and with no copy ever been sold for such price. If someone asked 50,- maybe then. It will create unrealistic expectations. Suddenly there is shitloads of "rare" records which never sell.
Anyways, this box has nothing extra really. Nice box, oversized, with t-shirt and button nobody is going to wear.
CD's are just the same versions as available individually.
According to current listings:
Forbidden Pleasures starting from 5 euro
Back For More starting from 4 euro
II not listed at this moment, but it's not extremely rare.
Instead you could grab Pain Provider 7" starting at 7 euro or first tape for 10 euro that are not even in the box but much more rare releases.
I bought the box when it came out, and I think it was expensive to make (actual plastic box designed for purpose of having these items, with artwork professionally printed on box. Not some cardboard & glued xeroxes type of stuff.
It's good stuff, if you like tongue in a cheek UK pe with test-tone type synth frequencies.