Keep your decorations and flowers simple. Check out your local grocery stores for flowers. You can buy them there cheaper. If you are crafty, you can use silk flowers, which can be reused later. Have soft music playing in the background on the stereo, or ask as friend to play the piano.
Many people take pictures at weddings for a few extra dollars.
You may even have a relative or friend who could do it economically. Be sure and ask to see samples of their work, and check up on their references. Design and make your own wedding invitations. There are so many beautiful papers available now. If you don't have an inkjet printer, take them to Kinko's and print them.