My son is travelling to the US in the summer for 2 weeks. He is currently on supplemental EN. He's reluctant to take an extra bag containing his shakes as he's travelling with 39 other teenagers as part of a lacrosse tour and desparately doesn't want to stand out. So my question is, is it possible to buy Ensure/Boost etc 'off the shelf' and, if so, where are the best places to buy it?