Bob, most places the cost of gravel is basically just the cost of the fuel and labor to get it out of the ground and to your door, or where ever. Just about every piece of equipment in the production line runs on diesel power, not just the delivery truck.
The price of anything made of steel has gone stupid over the last couple of years. Lines are nothing compaired to steel siding and construction metals. Many items have almost doubled in price...My pet peeve is the price of gravel.. Last Fall I was buying drive way gravel for $55.00 a load.. Right now it's 150.00 for the same load.. Fuel has not tripled so why has gravel....