You can use MPX4250 it reads both vacuum and boost. Combinig that with an ARDuino and some LCD will give you a very acurate pressure gauge that can even calibrate itself to current barometric pressure during a startup.
Data sheet of MPX4250
Prices are below 15$ so it won't kill your budget either
One more thing... Combining arduino with any MAP sensor from any turbocharged car should do. You'll just need to calibrate that properly to get accurate readings.