Giving the fact that pluck-a-pal gives you almost ALL the plushies i think this small list of low costing plushes not being in the spawn list is unintentional:
Cat Sack plush
Sack Cat Plush
Ram Plush
Dancing Banana plush
Alpaca Plush (It appears in the machine but rewards the llama plush which has already been reported)
Neither I or anybody that I’ve asked has seen these so that’s why i don’t think they can appear so correct me if i’m wrong.
I’m gonna have to agree with you on this since I’ve come across rare plushies before, and given that I’ve never seen those plushies you list after bagging ~100 plushies, then your list is either ultra rare by comparison or its a bug.
Haven’t seen any of these in the machines either, after ~200 plushies. I was trying to fill out my list so I was looking out for these exact ones specifically, I actually found this thread because I was trying to search about the alpaca/llama bug.