308Win. will be the least expensive of those you listed. It's the most popular cartridge
of those noted, and simple economics dictates that the more popular cartridges will generally cost less (22LR, 223Rem., 243Win., 30-30, 308Win., 270Win., 30-06 .....).
The more popular a cartridge is, the more loadings there will be available from the factories also.

If you want to check out relative ammo costs then take a look at some of the ammo prices on the following websites:

CheaperThanDirt: http://www.cheaperthandirt.com/ctd/default.asp

MidwayUSA: http://www.midwayusa.com/