My son loves all things space-related, so it was natural to have an astronaut party for his 5th birthday.  With a little creativity, and of course, the internet (for free clip art and ideas) and my color printer, we were able to keep costs down to a reasonable amount.  Our big splurge was to rent a rocket-shaped jumpy, but the party probably would have been just as fun without it. The invitations were homemade and printed on card stock (I bought a ream two years ago – it comes in very handy and is much cheaper than buying blank cards!).  A scoring tool makes a neat fold.  The outside read "5…4…3…2…1… Blastoff!".  Inside read "Travel to a Party Planet!", along with all the details.  The first hour of the party was free play – the kids spent the most of the time in the jumpy, but also played rocket with a huge cardboard box (free from an appliance store).  We gave them markers to decorate it as a rocket, and they had a great time drawing windows, buttons, knobs, etc. Then we gathered the kids together and told them that they were going to learn to be astronauts. First, we exercised (because astronauts are in good shape) with a game of Astronaut, Astronaut, Alien (a.k.a. Duck, Duck, Goose). Then, they colored small rockets (again printed on card stock). We used these to take an astronaut "driving test".  We used a poster of the solar system, purchased at a teacher supply store, to play "Land the Rocket on the Moon". After each child participated, they received a "NASA Astronaut in Training" badge, which I had created with free clip art, printed out on sticker paper, and cut into circles. Then we made and launched our own rockets. I found instructions on the internet (search for "seltzer rockets") to make rockets out of film canisters, using Alka Seltzer for rocket fuel. The kids decorated their rockets, then got to help launch them on the launching pad (a piece of scrap wood, covered with paper with a large red bull's eye target).  It was a huge hit!  My husband's only job was to help launch each rocket, so we could keep it safe.  Finally, we finished up with cake and ice cream.  I used the www.family.com rocket cake, which was very easy and turned out great.  My son handed out the goodie bags, which were plain black bags decorated with glow-in-the-dark star stickers, and had their name written in silver paint (using a paint pen). Inside were moon rock bouncy balls, flashlights with space theme shadow disks, freeze-dried astronaut ice cream, space stickers, fun-sized Milky Way bars, and Starburst candy. Everything but the candy was purchased online, and was surprisingly affordable. All the kids had a wonderful time, and my son now wants to decorate his room with space stuff!