cheap greensand in VA?
 

Greetings folks,

I am trying to garden very frugally, and I like the slow release
rock-based fertilizers such as rock phosphate, greensand, etc.

Espoma products are readily available, but they seem a little expensive
to me. Are there fiscal shortcuts I could take to find long-term
fertilizer sources of phosphate and potash?

Does anyone know of a cheap way to get rock phosphate, rock potash,
greensand, granite dust, etc. in Virginia (I live in Harrisonburg).

Thanks!