I try to use only stainless steel cups for my kiddos, but it can get pricey, so I’m always keeping an eye out for a deal! Amazon has the popular Klean Kanteen Kid’s Stainless Steel water bottle with sport cap marked down quite a bit if you choose the color “School Bus Yellow.”
This canteen is marked down to $11.30, which is a great price as these normally sell for $18.
UPDATE: It looks like you can also get the larger Klean Kanteen Classic Stainless Steel Bottle With Sport Cap in Dragon Fruit Pink color for just $10.15 (reg. $19) here!