i have a $8 simple metal scales with a clip to clip on a bag, and a bit to hold and the other bit swings down and says how much stuff weighs..

its pretty basic and not too accurate but its not bad, i like it a lot. goes up to 4ounces, has grams on the other side. fits in the palm of your hand, or in your wallet although it might get fucked up cos its just little and metal and you dont want it bending..

heres a picture if i can find it: