A friend has offered to ship me some of her milk and I am wondering, before I decide if it's worth it for her to ship it, what all is involved. Is there a guideline on how much dry ice is needed? I assumed dry ice and ship in a styrofoam-type cooler. Is there a certain way it's mailed through US Mail (e.g., priority, otherwise...). If it's outrageously expensive I'll just not have her bother although it was very sweet and generous of her to offer. I know some moms ship their milk while on longer trips so I just wondered if anyone knew or if I could potentially research the costs involved before giving her an answer. Thanks!