I’m fairly sure that the price information shown on a Google Search result page is advertising that comes from a different source than the results do.
As far as I know, you could write a plugin for SearXNG to query suppliers and format the output as required.
I think that Google Shopping might be queried in the same way, but I’ve never looked into it deeply.
Black Friday is a marketing exercise to get you all riled up about the massive savings you will receive if you buy something RIGHT NOW.
Suffice to say that the actual bargains on the day are far and few between.
If you actively track pricing you’ll discover that the price goes up before the event, then drops to the same or slightly lower pricing on the day. The “bargain” is notional at best.
Then there are the “pre Black Friday” sales, and the “Cyber Monday” ones afterwards. It’s all just marketing.
If you want an actual bargain, find what you’re looking for, set a price watch on it and track it for as long as you have patience. When you’re ready, buy it from your preferred supplier and get them to price match the amazing price.
As far as refurbished goes, ask yourself what is the upside for the supplier to give away any bit of return on their spend to refurbish the item in the first place?