Place votives on some or all of the tables to give the room a romantic feel as the lights are dimmed throughout the evening. The candles will also be a nice touch for all the pictures taken. Scented candles are a nice option as well.
Think Green — to save money on your flowers, try using more greenery than blooms in your church arrangments or garlands on archways, trellises, etc. Ferns and vines are both inexpensive and easy to obtain! Silk flowers are gaining popularity as well.