I've noticed different prices on the market and i'm curious. I know different species have different rarity. But colour wise, what makes a pet valuable?
It varies a lot, but it's mostly based on what people think is pretty/cool. Matching colors and colors that go well together usually do better than more random/clashing colors. Some popular themes are natural (colors that a wolf could be irl), celestial (night sky, sunset, aurora), pastel, greyscale, and some people just like collecting their favorite color.
The other thing that impacts value, color wise, is if the wolf is a wildwolf (randomly generated wolves found in the campaign). WWs are generally more valuable than regular wolves because they aren't related to any other wolves, and since their colors are randomly generated it's lucky to get one with nice/matching colors.