Generally I don't think TV show boxsets are worth it, before the big Buffy boxset each season was around £40 and not worth it, but for £130 for 7 seasons on 39 discs I think that is well worth it. I don't think any TV season as a boxset is worth more than around £20, unless it has more than the standard 22-25 episodes.

I think that the most I paid for one was when I got the Taken boxset, it is only 10 episodes but each one is around 90 minutes, that was around £35 at the time of release I think.

I have seen the Lord Of The Rings extended boxset for around £27 though, but it is simply the standard 4 disc sets in a larger box I think. I haven't yet seen a boxset of all 3 giftsets, the ones with the 5th discs per set and the book ends and such.