Find a large wooden dowel (such as a door stop for a sliding glass door) or any other pole life substance. Wrap it in cardboard and tape it up. You can spray paint it black if you want the full effect. At the top tape a tall aluminum and cover it with a black sock. Big headphones will also give a nice touch.
Get a cardboard box (we used a 30 rack of beer) and tape a cup to the front end. Also tape a small cardboard rectangle to one side to act as a display panel. You can make a hand grip on one side out of cardboard as well if you find it hard to carry. if you want it to really look like a camera, you can also spray paint everything black to make it look more realistic. An xbox live headset (or anything similar) will also add to the costume. Both boom mike guy and camera men look pretty funny if they have backwards hats as well.
Guy holding check: Whatever you want. We had him wear a shirt saying PCH: Prize Patrol but you can also dress up fancy as our announcer. The check is simply two pieces of foam board taped together will a little cardboard backing as support. See the picture for what to write, or you can personalize the check yourself.
Balloon guy: Buy balloons, have someone hold them.
Announcer: have them dress up in a goofy 90's looking suite, and make a microphone out of a toilet paper roll and rolled up tin foil.
Great hit at parties and large events, you'll get into all the pictures!