penny. My wife just makes the list as we use items and when we're ready to pickup, she'll submit it. You can allow substitutions or not as you wish. Often if you don't allow substitutions and they are out of an item you're looking for in a particular size they substitute the next size up free of charge (say a 12oz peanut butter when you've ordered an 8oz jar). My wife was concerned about them selecting fresh produce but so far they picked out item that were likely better than we would have done ourselves. A shopping trip that used to take us an hour to an hour and half now takes about 15 minutes (not including the list time).