What do you want to do with gold or USD if the us economy collapses? This isn’t the middle Ages where you can pay the peasants with gold or silver coins. In an economic collapse canned food, fuel, etc. will be useful. Something people need every day and can be swapped in small quantities.
This would be a bad approach, because you are essentially trying to brute force your way around a roadblock (no supported open data format) the supermarket intentionally designed. It would be easy for them to block your bot with Captchas, rate limits or IP blocking or just sue you.
You don’t need AI for that. All it takes is some standardized markup like schema.org and a discoverable price list page that can be read and understood by everyone.
We already had something similar with RSS, where you subscribe to your favorite blogs and forums, and the RSS reader on your computer would tell you which sites have new posts, so you don’t need to scan all of them each day. For some reason people stopped using RSS, and instead published their stuff (or notifications about new posts) on Facebook, twitter etc.
The same system could be adapted for (grocery-) price lists. However the big brands would never do that, because then it would be very easy to discover which products suddenly got more expensive.
But who wants to trade gold with you if everyone is hungry, has no water or power, is freezing or sick? Gold and valuables are only good of you know the economy gets back to normal, or you have someone who will trade useful stuff for gold.
Also, I don’t think the average person has a concept how much gold is worth, or how to check if it is real or not.