Hi new here, but not to Steelbooks and it's my first post. Just to clear things up from the UK point of view.
Alien 1-4, Predator 1-2 and Alien Vs Predator 1, were all released as DVD Definitive Edition Steelbooks in G1 size in the UK. As stocks started to run out in stores, these were replaced with slip cased G1 Amrays, with identical cover art as the Steelbooks. Then as stock of these became short, the cover art on the slip cased Amrays got a slight tweak here and there. So in some cases, there are three versions of the Definitive Editions, just depends on the popularity. So be careful!
There was no DVD or BluRay Steelbook of Alien Vs Predator 2 released in UK, but there is a Dutch DVD version in G1 size.
Then came along Predators, which was a Play.com exclusive and was a G2 triple play Steelbook in the UK.
I have all of the above Steelbooks if you want any photos.
Personally your best bet is Ebay now, but I would always contact the seller first to confirm that is a Steelbook, they ship internationally and also they provide suitable packaging. From my own experience quite a few sellers just put Steelbooks in a bubble bag and then whinge when you complain it’s arrived dented.
