| the biggest expensive in building a turbo is not from parts, but tuning and dyno time. The cheapest way to do it is probably megasquirt, but you have to make the board yourself. Turner motorsports also makes mail order chips, but i wouldnt trust anything but a standalone, laptop, and dyno time. hope this helps.
other option is a pre-made kit, which should come with pre-tuned software | 
Linear Mode
