Bulk ammo for .300 win mag at Cabela's is $119/100
Hornady custom handloads for $37 per 20
Hornady light magnum $39 per 20

Didn't see anything for .300 win mag for $85.

Maybe you saw some Weatherby ammo. It can be a couple of dollars
each just for the Brass. Different calibers tho. Specialty high
velocity chamberings.

.300 win Mag- a common elk etc. round and used by long range
snipers.