Does it have to be new? Can you do your own build?

I'd consider something like the 42cm Soma Buena Vista Mixte bare frame with 26" wheels.
Buena Vista (Complete Bicycle) | SOMA Fabrications

Then build it to your specs. Even do your own paint job.

You mentioned a "Kid's Bike".
You can always rebuild it with your own components. An Ultegra Mini-Group (Shifters/Derailleur) is only about $300 at Ribble. Or, your components of choice.