They sell it like that here too. It's sand for cement projects. Some people run it through a drywasher before using it as the plant it comes from here is in a gold bearing area.
After synthetic lawn is rolled out and anchored in place, they usually back fill and rake in sand. I was told it's a "special" sand; probably screened for size.
Decades ago we had to buy a lot of topsoil (long story). The first couple of dump trucks were said to contain 10 yards each, the third (a semi trailer) was said to contain 16. I believed the driver but my friends with tape measures and calculators said I had been scammed.
We have a large plastic bucket from our old days of wine making (it's 2 or maybe 3 cubic feet). We go to the local landscape company and ask, "How much for that bucket full of xxx?" Usually it's a couple of bucks. We fill it and put it in the car and off we go. We've done that with a half dozen bucket's full too in a rented half ton (that we had rented for another purpose).
We carry small amounts of lumber in the car too. If you carry padding and load it carefully you can put a number of boards (10 footers as I recall for the Honda) through the fold down rear seat and stacked between the front seats. You don't want to stop fast of course but for us the trip is only a couple of miles.
Cheaper than a delivery fee which is about $80 here. And yes we're cheap.