Look into making your own Soil Conditioner... here's a good post to check out.
Per the city's website " The price per unit for bulk is: $12 per cubic yard for 1 to 10 cubic yards, $8 per cubic yard for 11 to 500 cubic yards and $6 per cubic yard for 501+ cubic yards. See the Delivery Options tab below for details on delivery fees and service area."sicride said:The point of top dressing is to increase organic matter and microbiology of the soil. The organic matter is what helps with water absorption and retention, the microbiology of the soil (living organisms) are what will release the nutrients to be taken up by the plants. This would be best applied immediately following aeration to help incorporate into the soil quicker and more efficiently. If by a truck load you mean a dump truck this sounds like a good deal and is approaching the correct amount needed to top dress 15k each season. If that is a pickup truck load... Keep looking, you'll need a lot more than that.. A LOT.
Most importantly, get a soil test done and give the soil what it needs!