The best beans I've walked have a ton of gypsum under them.  That is around $30 per acre here but varies widely across the Midwest.  I am thinking you are in Indiana so I don't think you are that far away.

Beans need lime and respond to Calcium and Sulfur.

Inoculants are always a good return on investment for me but fusariums like SDS have made nodules soft and mushy where the farmer may not have followed these practices.

Ed