No offense GroundControl, but as SouthernGreenScapes said (minus the tone), you should really know what topsoil is. "Topsoil" is not really MADE, it's naturally "deposited" over a very long periods of time (an true inch takes hundreds of years.) What an excavation company will dump and market as "topsoil" will be sod, topsoil, and majority CLAY and possible rock. I would do some serious research if you want ot find a good source. A screen or shreader is expensive for an onsite operation. Then you'll need a good loader. And you'll need dry storage.
Topsoil has around 8-10% organic material in it. Some supply yards sell a "Landscape" or "Perennial" mix that is premixed and contains sand, compost and (hopefully) a decent topsoil.