Invitation/save the dates

Normally I'd suggest looking on etsy, but if you can't find something there, maybe reach out on a local wedding facebook group and see what they suggest? The one I'm a part of is SO good at suggesting decent local vendors!

I would say go on Zazzle, and touch base with some of the artists whose designs you like.

Do take a look on Etsy for illustrators (including children's book illustrators) and I think you will be pleasantly surprised.

Another potential route is looking at illustrators/artists on Instagram and reaching out to them on their business pages.