Change in price over time is irrelevant for making a decision on whether or not something is worth the utility to price ratio now. If you are trying to time the market on junk food, then it is best to simply avoid it.
If, for some reason, you want to prevent Mondelez, or whichever other manufacturer, from earning more profit margin than it historically has, then you can look up their public financials most of the time:
https://www.macrotrends.net/stocks/charts/MDLZ/mondelez/prof...