These lists will help you buy the materials you need to get started

Also see the IllustratedGuide for a downloadable PDF with a simplified set including assembly and use instructions.

Helium

• In the US, helium costs ~180 dollars for a large 240 cubic foot tank, or ~60 dollars for an 80 cubic foot tank. 80 cubic feet should get you 2 flights with a 4-5 foot diameter balloon, enough to lift a camera.
• Measure how much helium you'll need to lift your camera with this handy table.

Beginner/low-cost materials list

• one balloon balloonsdirect.com
  • 35 dollars for a 5.5-foot balloon, or 24 dollars for 4-foot if your camera is light
  • alternative: 1 or 2 giant (95 gallon) trash bags and plastic packing tape
    • balloons made of trash bags or even better, mylar sheets, are more durable (won't pop as easily) and cheaper. They may also retain helium better if you leave them inflated for more than a few hours. See discussion on the mailing list
  • 1.50 dollar mylar emergency sleeping bags
• 1 2-liter plastic soda bottle (rounded, not conic neck works best, see SodaBottleRig)
• 600-3000 feet braided nylon string, like kite string, mason line, anything strong and very light.
• duct tape & clear packing tape
• a cheap digital camera with Continuous mode shooting. (where you can just hold down the button and it takes repeated pictures), and a rubber band to pin down the button
• helium to fill the balloon to about a 5-foot diameter

Advanced/high performance materials list

• $12 Ball-bearing compact kite reel
• $130 2500 yard 30 pound spectra fishing line (dark colors probably show up less in photos)
  • Alternatively, more options in more colors, lengths, prices and weights
• $15 55"x50' 1 mil metallized mylar roll for making your own giant lightweight balloons* 40-60 cubic feet of helium
• clear packing tape
• two 12" dowels, 1/4" diameter to build a Picavet suspension (see BalloonAerialPhotography) or use a SodaBottleRig
• an old canon camera (check compatibility on http://chdk.wikia.com/wiki/FAQ#Q._What_camera_models_are_supported_by_the_CHDK_program.3F)
• If you're going to be doing a lot of this, consider buying an aluminum helium tank, which you can keep as long as you like, and which is much easier to carry: 280 dollars for 125 cu feet (~2 flights) or 180 dollars for 55 cu feet (~1 flight).