Depending on the bullet/ammo selected the prices vary, as does availability for OTC ammo. However all things considered equal in bullet styles/brand the prices here are as follows: (lowest to highest)

22-250 and 308 pretty close to the same price

22-250 is cheaper by a few bucks here but less variety and less applicable uses - the 308 is much better suited round from varmits to biggame)

270 and 3006 -Equal

availabilty is equal, larger selection of ammo and grain sizes goes to 3006)

7mm and 300 win pretty close to the same price

availability is equal, equal ammo selection and uses(except big bear - Griz, Browns, etc where 200 grain is desired -300 win would get this nod). Here the 7mm mag is few bucks less a box than the comparable 300 win