You need a laptop Win7 64 bit, the faster proc. the better, at least 4Gb mem & reasonable Hd. You can find used Dell's for around 100$ then you need to buy
this here
Then you need to get familiar with the software. Normally when programming, you need a 40Amp power supply (newer BMW's need 70Amp). They prefer the Deutronic DBL800, but it's very expensive.
I was successful using a 12 Amp battery charger (not recommended for programming) so your risk.
The cheapest power supply I found is around 450-500 Us $, which is out of reach for me looking at the exchange rate from CAD.....