Not worth it at the dollar store: foam plates
Also an essential on your party-planning list. At the dollar store, a stack of 20 foam plates (9-inch size) are just 5 cents per plate. You'd pay $4 for 80 plates at the dollar store but a package of 75 plates at Wal-Mart costs $2.75 or just under 4 cents a plate. You save $1.25 for only five fewer plates.
You can get a lot of cheap party ware at a dollar store, but going for the lasting products -- a set of plastic or china dinner plates -- might not be your best option for a party, especially if you're hosting a large gathering like a wedding.