historically, some luxury or specialized products have been known to have extremely high markups. For example, some high-end fashion items, jewelry, or luxury watches may have markups of several hundred or even thousands of percent. Similarly, certain medications and pharmaceutical products have also been notorious for having substantial markups.
It's essential to keep in mind that markups can vary significantly between industries and specific products, and they are often influenced by factors like production costs, brand reputation, exclusivity, demand, and market positioning. If you are interested in the highest markup for a specific product or category, I recommend searching for recent data or consulting industry-specific reports and analyses.