I have this one that I got when I bought a whole room at an auction for less then $10. Scrapped the metal in the room and kept the scale...I verify I had the same weight when I drop off at the Fedex Depot and it has never lied so far. Needs no power and has a lock on it when the box is too big to see the dial. Only goes to 100#'s but most packages sent out are less then 70#'s and if I'm weighing something heavier I divide it into smaller lots. It travels well too.

Pelouze Scale Model P100S 100LB Scale Weigh Scale Shipping Scale | eBay