Shoppers are out in force this Memorial Day weekend, but they're being very strategic about opening their wallets, according to a new survey by Retail-Me-Not. "What we're seeing is more people are showing up for Memorial Day sales this year than they have in the past, but they're bringing less money," said Stephanie Carls with Retail-Me-Not.The survey found 54% plan to shop, which is up from just 36% last year. However, the amount they plan to s…