You know those 3, 5 and 10lb bags of produce at the store? Apples, potatoes and onions, especially come in pre-packaged 3,5 and whatnot sized bags. Well, did you know that when the bag of apples says "3lb" it does not mean that there is only 3lb in it, but that the minimum has to be 3lb. So I started weighing them, and turns out, most of them are 3.25lb, some are 3.5lb and I have even found a few almost 4lb. Now I don't stand there and weigh them all day, I look through the stash, pull out the ones with the best looking produce (no bruising, rotten spots, etc) and then I weigh only the best looking ones and buy the one that weighs the most.
This is one of the many wonderful tips I picked up out of one of the editions of "The Tightwad Gazette"
If you have never read the tightwad gazette I, II or III - I highly, highly recommend it!