I bought a gallon a few weeks ago and I can't remember, maybe $10-12 USD???
I primarily bought it to have some on hand in case I needed to top off the radiator. As it turned out, I had a block heater installed during my 50 hr service and the mechanic had to drain the cooling system to do this. He mentioned that I should check the level the next morning (he did the service in our driveway). I checked and it needed some more, so I added some FleetGuard.
The thing that bothered me was the color of the antifreze in the radiator. He must have used Prestone because it was Prestone green. I didn't think Prestone made antifreeze for use in diesel engines.