That Quadrilogy boxed set is a nine-disc collection that packages all four of the two-disc special edition DVDs alongside a ninth disc that contains yet another set of bonus features. I'm with the others -- the last two Alien movies are not worth buying. The $70, the Quadrilogy is still fairly pricey, and the only reason for buying it rather than the individual titles would be that extra bonus disc, which includes a new hour-long documentary and a few extras ported over from previous LD releases.

Keep in mind that Fox has already re-released the Alien series as budget-priced single-disc versions, so if you are at all interested in any of the individual titles, you might need to pick up the two-disc special edition sets soon. The versions that came with the Quadrilogy set have those cardboard Digipacks, and only the first and fourth Alien movie come with DTS soundtracks.