Tis quite confusing when looking at American recipes sometimes. They use different things than us and I can never usually find a definitive answer. I didn't want to use too big a cup and throw off the rest of the ingredients. =)
you do need to be precise when baking, and liquid isn't the same as dry stuff in english cup recipes sometimes, anyway I was fed up converting recipes all the time so i got mune from Marks and sparks, but somebody said Poundland - there you go can't be bad!!