Have you heard of Litebox? It’s a website which collects rates from illustrators, cartoonists and visual artists and publishes them in a searchable database. It’s all about encouraging transparency in the industry. I’ve been searching for something like this for a long while and I’m so glad to learn it exists.
By the way, I learned about Litebox through Studyhall - an amazing resource for writers (and other media folks) which I cannot recommend enough.