I bought my arduino from Partco Oy from Helsinki (in Finland). You can buy it from there too or fro example from amazon.com. There are thousands of arduino parts in amazon.com.
How mucht it cost? The smallest arduino cost’s only about 10 dollars, but the laargest arduino cost about 80 dollars.
Some of arduino parts can cost nearly 200 dollars like arduino 3G shield. But the cheapest arduino parts can cost less than 1 dollar.
Arduino projektini 
Could you recommend some models from Ebay or from Partco Oy? Which are your favorites and why?
My favourite model is Arduino Mega 2560, because there is sure enough outputs pins (digital and analog outputs and inputs). Partco Oy doesn’t sell very much arduino parts but it sells thousands of electronic components. In amazon there are relay shields APC220 wireless module etc. very interesting and funny parts, but electronics is so expensive, you know.
Here you can see arduino and arduino parts in amazon.com: http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=arduino
Tää nyt on vaan pientä huenostelua, mutta korjaisin että Arduino Mega ADK maksaa enemmän. (muistaakseni 70€)
Ok. Hyvä tietää. Mitä eroa ADK:ssa on 2560 verrattuna?
ADK:n voi yhdistää Android- puhelimiin ja tehdä puhelimelle ohjelman jolla Arduinoa voi sitten ohjata. ADK sisältää myös kolmiväri Ledejä suoraan Arduinossa kiinni.
Very nice to know this. Do you have a lot of experience of Arduino, how long have you been interested about this kind of stuff?
I haven’t had Arduino more than one month, so I don’t have so much experience of Arduino, but I have two years experience of coding and about seven years experience of electrical stuff. So I have been interested of electrical stuff about seven years, programming about two years and Arduino about half a year (but still I have had Arduino only one month)
And thank you Ossi for your activity in this site!
Nice site Elias Ojala ! You have seen very much work about this site.