I have a Stren digital and it's pretty accurate. It reads pounds and ounces. A gallon of water weighs 8.333 pounds. Add an ounce or so for a plastic jug. When I hang the jug from the scale it reads 8 pounds, 6 ounces. I paid about $20 for it at Sports Authority.
I used to have the same scale Franklin is refering to - it's a good scale and easy to use. I have a scale from Berkley right now but it's off by a few ounces and I think I'm going to get another Rapala. Good luck!