We'll need a few things to start:
- An Arduino. It doesn't matter if you buy an "original" one like the Duemilanove or Uno or a clone like the Diavolino. They're almost identical. If you've got already some soldering skills, you can build your own clone too! The Arduino is "Open Hardware", so there are many legal clones out there. Most of them act like the original, some of them are made for special needs. So before you buy one just make sure to select a "regular" model and make sure, that you get one with a standard USB port.
- An USB cable (A to B), if you don't have this kind of connector on your Arduino you need a special cable like a FTDI adaptor
- A red LED. If you want to save money always buy LED bundles. These contain several LEDs in different colors and sizes and they're really cheaper than bought one by one. Check out eBay. Don't buy SMD LEDs, these can't be used for prototyping (ok, you can use them, but it wouln't be funny at all....). Another option would be to desolder a LED from a broken device. I often use parts from old devices. They're for free and it reduces the waste and you'll level up your soldering skills without spending money.
- The programming environment, you can download it here for free: http://www.arduino.cc/en/Main/Software
(Linux, Mac, Windows)
- a copy of "The IT Crowd - Series 3 - Episode 4", no you don't really need this, but you'll really enjoy it, if you're geek like me
- solid core wire, if you don't want to buy it, just take a look if you've got an old computer with an internal speaker. If you don't need it any longer just clip it off
- soldering iron and some solder
- project box, you can use anything you like.