The single serve cartons of milk are shelf-stable, so you could stock up on them if you have the pantry room! Then just put them in the fridge to chill; they would travel well in the small carton size.
The sugar content in the flavored milk is a bit high, however it is the same in another brand of flavored milk ... the biggest difference is in the ingredients. Horizon's shelf-stable flavored milk only has 5 ingredients (and their refrigerated flavored milk has 9) and the other brand of refrigerated flavored milk had 14! I don't buy flavored milk that often since Kayla drinks plain milk just fine, but she really did like the vanilla flavor! The reduced-fat plain milk tasted yummy and creamy right from the fridgerated carton.