Thanks for the replies! Unfortunately we bought the acrylic cage from someone on eBay who seems to no longer vend through eBay. Plus, there was just no way that repair could happen. The latch was attached to the body of the cage and took a chunk of the cage's body out with it when it got ripped off. The cage lasted a couple years, but it was a bummer.
Sarah, agreed that foldable is the way to go! Or Sennie has a buzz saw habit. He easily chews through wood, so while I had considered the cages you suggested, I was afraid he'd inflict major damage to the bars' finish somehow. I kinda bit the bullet and splurged on the smallest aluminum King's cage. Got a decent price through someone on eBay.
There are definitely pluses and minuses to each of these carriers. So we went through the acrylic cage. Never again. For one thing, while ours had plenty of breathing holes (actually breathing slits was more like it as they had cut the acrylic in an almost bar-like fashion), it's just not practical for the bird inside to try to walk around on solid acrylic "bars." On the other hand, the bird could see out the acrylic, which was great for socializing him, but also made for some anxiety at times (and could be scary where we live due to lots of birds of prey about). Also, the cage we had was definitely heavier than one would've imagined for something acrylic.
We have the Avian Adventures Poquito Avian Hotel. I think a few others here have it. It's heavy as heck since it's made of powder-coated iron. But it's definitely sturdy, folds down, is economical, and provides a nice amount of space for a smaller to medium bird who will be away from their home cage for days and days at a time. The locking mechanisms are kinda finicky. You've got to make sure you screw them down good. Other than that, this cage is our workhorse for weekends away from home.
The King's cage I was told is the Mercedes Benz of the cage world. It's very sturdy yet lightweight. But it comes at a cost premium. The other amazing thing about the small size cage (and perhaps others?) is that there is no bottom grate! The acrylic cage also didn't have a grate on the bottom. But for that price, you'd think they could've set it up with a bit of a grate so your bird doesn't walk in its own poo! So I was somewhat disappointed by that design aspect. The Avian Hotel has a bottom grate at least.
The major design flaw both the latter cages have are how low the food cups are. Then again, maybe our Sennie is just kinda dumb and poops where he eats. But the food cups are definitely set up to be lower than I'd like. So we usually get other cups and put his food in those instead. Definitely cuts down on him pooping in his water and food.
We also own an Adventure Pack backpack style cage. While it's stainless steel and very light weight (much more so than even the aluminum cage), the cage is very flimsy, and almost needs to be reinforced by the blue canvas backpack to prevent fly-aways. (Smarter birds would definitely have a ball figuring out the latch mechanism!) If you're not sure what I'm talking about, here's a vendor to show you the cage:
http://www.parrot-and-conure-world.com/adventure-pack-cage.htmlWe've used it to take our guy on hikes with us. It worked well for that. But I wouldn't trust it for longer periods of time, and certainly not without the canvas making sure no one escapes. The other major drawback is that, unlike the King's cage and the Avian Hotel, it doesn't fold down at all.
Anyway, those are my opinions as someone who's gone through almost all the carrier cages out there. Never owned those backpack style ones, though. Since PeeWee chews through canvas shoe toys, I doubt I'd ever go there with him.
