Bigger bore and higher price?

Ok, so as I'm browsing through Wal-Mart, they have a .30-30 Marlin for $275. The .44 mag I was looking at before would run around $600 at the gunshop. Now, I know gunshops charge more, but the .30-30 was cheaper at the shop as well.

My question is why does a smaller cartridge cost so much more? Granted, the bore will be larger, but isn't the .30-30 a more powerful round?

Any input would be appreciated. Thanks.

O Lord,
grant me the Serenity
to accept the things
I cannot change
the courage to change the things I can,
and the supreme firepower to make the difference.