Thanks all for the responses. Great point regarding the $0.40 per pennant shipping cost.
Agreed...whatever I'd save in shipping cost would be eaten and then some buy the cost of the foam core. Guess I'll just stick to my current method of saving and re-using the cardboard from previously rec'd pennants.
But that just means I'll have to buy more pennants for my collection so I don't run out of shipping supplies.
