I too, have a conical
spreader from Agrex. (3 pt - PTO) Got mine from my local JD dealer. I wanted one that would "resist" the fertilizer corrosion, and this one has a plastic cone for the material and a stainless steel whirlybird mechanism, rather than just regular steel. Going on my 3rd season with it, and still looks like new. I rinse it off each time, and have no corrosion, and I spread 60+ bags of fertilizer a year, plus other stuff like prodiamine, insecticide, etc.
The ability to control the spread is a real plus. You can regulate the amount, not just by the gate opening, but the tractor speed, elevation of the spreader on your 3 pt.
Paid $995 for mine.
Good luck!