Weight and bulk vary, but a yard is 27 cubic feet. Garden soil at stores is sold in bags containing 2 or 3 cubic feet. So a yard of soil would fill 9 to 14 typical bags. There is roughly 1-ton of soil in a yard. The typical dump truck can transport 8 to 10 yards (tons) of material. Quality of top soil varies widely and depending on the source may be poor in organic material, or may contain weed seed. Most is screened for size. The price you saw is very inexpensive and probably does not include trucking.