Jack's House of Buggery

To a degree, yes. But since comics retailers are almost all small businesses, most often very much so -- unless you're buying your comics from a 'newsstand' or grocery store, in which case find a local independently-owned shop or a more distant one which will ship to you -- they tend to be closer to their break-even than may be apparent. Think about how much shelf space in your store is taken up by back-issue inventory, and how slowly those issues move compared to current ones. And remember that retailers have to pay up-front for every issue they buy and hope enough sell that they can make their rent and payroll.