[Kate]

I don't have kids but these markers are so cheap I might just have to pick them up! There are a couple of options:

Crayola 12-Pack Assorted Markers - $0.97
Crayola 10-Pack Assorted Broad Line Marker - $0.97
Crayola 10-Pack Ultra-Clean Washable Markers, Fine Line - $3.49

Shipping is free and there's no minimum order charge!

This is Staples.com so I assume it's US-only.