Since many of your guests are coming in pairs it won't be too difficult to place them at the table. And if you're looking to play matchmaker at the single's table you can ensure that your friend sits next to the guy you always thought she should meet.
Place cards will add money to your stationery budget. Talk to your stationer about using a design that matches your wedding invitation exactly or something less expensive that compliments it. Another way to save money is to combine the place card with another item on the table, such as a menu card or favor.