I found this fun, easy, cheap way to have fun with bubbles on a blog called The Muddy Princess.
-Plastic water bottle
-Old wash cloth (that you don't mind cutting up)
First, you cut the bottom of the bottle off and attach the washcloth to the bottom with a rubber band. Second, you fill your bowl with a good squirt of dish soap and some water.
I first had my 5 year old son practice blowing (not inhaling) into the bottle. Making sure he knew that if he inhaled that the bubbles will come into his mouth. (which wouldn't be pleasant)
Next dip the bottom of the bottle into the soapy water and blow into the top of the bottle. If you blow slowly the result will be a huge snake bubble. It was fun seeing just how long we could make our snakes.