Wellcome Gourmet stores have more imported foods than normal Wellcome stores. At the Miramar store, I found some great buys---including Sugar Free chocolate bars for $85 each (I have some diabetic friends who can only have sugar-free products, and this price is reasonable for a large chocolate bar).
I also found mini marshmallows, which are harder to find, for NT$49/bag.
Wellcome Gourmet carries a large selection of canned beans, olives, potato chips, and pasta sauce. The prices aren't dirt cheap, but if you need something in a pinch, you can probably find it there.
Now if they would only start carrying natural peanut butter...
