they have some at this "pop culture" store at the mall nearby. thing is that they're ~$20. I'm a fan and all but I don't want to break the bank. they had a lot to choose from, though.
I haven't yet, but I do intend to get a couple and when I do, they will be from Amazon. You should be fine purchasing from there. Just check the reviews first and obviously choose which one you think looks a better quality. I'm going on to have a look for my own in a moment
I've gotten Cyrus and Rover as gifts, I'm pretty sure the company that made them is called San-ei. There's nothing really specific you need to know, they are pretty soft and, while I don't play with plushies in a way that they would get easily ripped, they seem durable to me.
I have a K.K. Slider plush I bought from a discount store a few years ago. They were also selling Rosie and Bunny plushies. They were Tomy, as far as I recall. ^^ It's a shame, had I known how expensive AC plushies were normally, I would have bought more.
(I still have my eye on a Fauna plushie, but I just can't justify it right now. Heheh.)
i have an isabelle in her fall outfit plush that my bf bought for me im not sure where he got it -- he just came home with it one day and i was just so excited that i didn't ask. haha. we live in seattle so there are a lot of places to get merch! tho i have browsed amazon for plushies, and the one i have looks similar to one of the off-brands you mentioned. she has a little bell like the real isabelle and i love her :3