Such as the ones at publix, that they inflate for you. How much would one of them cost? ballpark it?
the balloon, latex, would probably cost you about a dollar, and a shiny one about 2.
How Much Is A Balloon
The other answerer is about right for what it would cost to buy one filled from a vendor. If buying them in a pack from a store (uninflated), I would expect the cost to be much lower: probably a couple of cents. Maybe less than a cent for small balloons if bought wholesale.
go to the store and ask the freakin salesperson