The home video market is shifting, and often the best way to view a movie is a disc from a boutique label or a foreign market. I think most K owners will need to augment their movie library now and then.
For casual disc buying of mainstream titles, Amazon, Walmart, and Target are all viable options. The search function on Amazon has recently turned into pure garbage, so it's easier to just Google "Aliens 4K UHD Amazon" to get the direct link. With all three of these, you're at high risk of receiving your disc in a mailer (cardboard or bubble). Adding gift wrapping will ensure you get a box and extra packaging, but they could still put a dented up/knocked around disc inside.
Much like the disc market has shifted to boutique labels, disc purchasing is also shifting to boutique stores. If you want the widest range of discs, including foreign, specialty, etc., then you're going to want to try stores like DiabolikDVD, GrindhouseVideo, or my personal favorite: OrbitDVD.
Allow me to be a commercial for OrbitDVD for a moment... While the mainstream stores throw your disc around a warehouse, these folks treat their discs like a collector would. The listing says whether an item will have a slipcover, and you can expect to receive an item carefully wrapped in bubblewrap and packed in a sturdy box. If there's small damage to slipcovers or box sets, the stuff that's nearly unavoidable at the mainstream sites, these folks will add descriptions and photos to the item in question. They carry a wide range of obscure stuff, get plenty of foreign offerings, and even buy collections and sell used titles on their site with detailed descriptions and photos. And, yes, they'll get things like Andor, True Lies, Live Die Repeat, etc. (They also have a Facebook page where they upload photos as they receive restock shipments, so you can browse the discs before they're stocked on their website; great for rare finds.)
Finally, for foreign discs there's the various global Amazon stores. Amazon Japan has the Marvel 3D discs since Endgame, Amazon Germany is getting more and more exclusive 4K releases, and Amazon UK and Amazon France are also great sources for Region B titles not yet in the US.