top right hand corner of the list view... select the sort order and pick "price (low)" or "price (high)"

https://markups.org/?sort=price-desc

Thanks! I had tried that, but I guess I saw the kinds of cars at the top of the list and assumed that "price" meant "actual price of the car",

I was looking for something labeled more like "markup as a percentage of what this car was actually worth".

A dealer with a $1,500 markup on a car worth only $1,200 is much worse than a dealer with a $20,000 markup on a car worth $80,000

I guess it just makes sense that they'd be able to throw a larger markup on cars which are that much more expensive to start with.