Don't forget accent chairs! A gorgeous modern accent chair can really make a room - and offer extra seating, so don't just stick to an elegant sofa and loveseat. You can get well made leather or upholstered accent chairs to finish a room for great prices.
If you like to shop antique fairs or flea markets, look for well made mission or contemporary shapes - try for hard wood if you can. You can reupholster or refinish anything you find. Think of the satisfaction of looking at the chair you brought back to life! If you don't want to invest the time in refinishing, look online for discounts or wait for the right sale for your clearance furniture.