ArduinoIDE on RaspberryPi

Where can I order a rasppberry?

Those are the only two places you can order them from.

First you register an interest, then they log that and put you in a queue, then they invite you to order one.
I have been sent today by RS, a unique activation code that will allow me to order one. However, I ordered one on the launch day from Farnell and was sent an email yesterday saying it had been dispatched so I am expecting mine tomorrow.
They sold 100,000 on day one alone. There is a bit of a backlog.