As far as I know, Costco isn't costing taxpayers money in order to offer their low prices. Therefore, what you pay is really what you pay. What you pay at Wal-mart isn't really what you pay after you figure in subsidies. I believe in a capitalist system, not a halfway system where they pay their employees barely enough, then the govt picks up the rest.
And as I stated above, my prefered shopping choice is Target. Higher prices, but higher quality merchandise.
Secondly, you keep talking about subsidies that Walmart receives that Costco doesn't. What exactly are these subsidies? Are you saying that a failure to pay an employee a particular amount that you deem to be sufficient amounts to a subsidy? In your view of free market system does that mean that every employer that is paying an employee a minimum wage is receiving a subsidy?