In the Way of Decorations
Use last year's, if you will have them. If you don't save the decorations you buy this year for next year.
Make your own,
they don't have to be to fancy. Or you could print some cut-outs you can find on Family Crafts at About.com.
Instead of using a catering service make the food yourself, or better yet have a pot luck.
Just have snack and finger foods opposed to having an actual meal.
Throw a BYOB this year, that way you are only supplying the alcohol you drink.
You could also supply alcohol but have a cover charge and make some of your money back.
Print them out, or make the instead of buying them from the store. This will give them a personal touch which makes them better anyway!
Remember to stay safe and have fun!