[acdha]

Yes, and plenty of cheap ones, too — you have a pretty good range based on features and looks. This kind of complaint is pretty predictable: most people who want one will drop $100 on a normal VESA stand or arm, but the Apple one is definitely competing with people who either want the matching designer image or simply aren't that price sensitive.

Here's an example of Herman Miller, which is definitely competing for the same kind of buyers with a $450 monitor arm:

https://www.hermanmiller.com/content/dam/hermanmiller/docume...

Now, they do at least discount that a bit so a good question is whether you'll see the Apple ones showing up at less than list price:

https://store.hermanmiller.com/office-furniture-desk-accesso...

[barkerja]

Are these arms large/long enough to allow for a 27" to go portrait?

[acdha]

There are definitely arms available for almost any size or weight range you can imagine, but the heavier weight-rated ones tend to be pretty utilitarian since there's really no way around the physics of a weight on a lever arm.