I'm guessing, but I think you'd have really good luck at any of the Chinese grocery stores. That's where we used to get it when I was a kid, but I haven't looked for it in years. As an alternative to Ovaltine, you can get Horlicks, which is pretty much the same thing.
Where can you find Horlicks in the area? I've never seen it at an Asian grocery store, but to tell the truth, I'm not often looking for it at an Asian grocery store. Love the stuff, but I usually wait til I schlep out to the British Pantry in Aldie, VA.
I'll take a look at the Lotte in Germantown this weekend, but I'm the same as you. I never look for it but I know I've seen it around before. If I find any, I'll let you know. I used to eat the Horlicks candy when I was a kid, but I haven't found that in the US in years...
This was in Saratoga. I wish I could remember which aisle, but it was toward the front of the store on the top of the aisle, and I think other mixings like hot chocolate were there too. It was definitely three different kinds of Ovaltine.