It’s not confusing at all. The only way I know to get product data is through an API. When you find an API you want to use, you can follow my tutorial video to learn how to extract the JSON values you need: API JSON Tutorial (Video).
I don’t know of an API that shows current prices of products in stores. That’s probably the trickiest part of what you’re wanting to do. I would start by Googling something like grocery price api.