I lived in Brasil for a couple of years, and everywhere I went I would see these stainless steel drinking glasses. No one could ever remember where they got them, because it had been so long since they had bought them. It took me a year and a half of searching before I finally stumbled across some at a hardware store for $0.25 each. I bought a dozen of them. I have been using them ever since and still love them, although the quality of them isn't the best and some of them are starting to show some rust stains. The other day at Ikea in the bath section I again stumbled across the SEMVIK tumbler which is almost identical to the ones I bought in Brasil. The price is a little higher at $2 each, but for a cup that will last a lifetime, it's worth it. I bought 4 and plan on buying a couple more next visit.

Available at Ikea for $2.