free.
after you decide what items you should buy, take your time to go shopping. look for sales in order to save money.
if you are having the party indoors it will make your job easier. fill the room with stars, hanging planets, the moon, the sun, and even a spaceship!
you can even print images of the night sky and put them in the ceiling for a more realistic feeling that you are somewhere far in the galaxy!
if your wish is to have the party outside, you should consider starting the party when the sun goes down to have a good look at the stars.
make biscuits in the shape of stars, sun, 