RE:4P's
Note from the article:
Rugged gravel, which goes through less finishing, costs closer to $30 per ton, but the edges are sharp, which makes it less attractive as a ground cover option. Pebble-type gravel costs closer to $90 per ton.
Take into account location and delivery as well as supply and Demand.
4C's assessement at 40, 50, 60 per ton is a realistic number when putting together quotes for construction companies bidding on projects.
best,
c