It's really interesting looking through this thread, especially the slumber party pets. I used to have SO MANY of them back in the day and used them as trade fodder - when they weren't worth much at all. I do wish trading so many of them off, sometimes! I definitely traded off my white creep but at one point had three black creeps knocking about... oops.
I don't have trade data for those older pets - but I can share my trades for the golden gacha dog! I sent these trades a while after the litter came out. I found out about it and NEEDED one, so I'm not sure if this was after the value had settled or not.
Here's the first trade, I paid with an 09 VR rat
Here's the second - I can't remember when for the life of me that BW is from.
I definitely overpaid, but I was more than happy too because I NEEDED this dog lol
I also find it interesting seeing the PPS coocoon BW; I didn't even remember that pet until I was sorting mine out recently and found it tucked away in my folders. I had no clue it had such high demand!