How much it costs depends on your resources, how much you know, and how far you want to go.
You could get some mandrel U bends for intake piping from JC whitney, a used T4, custom exhuast piping, and a piggy back fuel management system (not including a new pump and injectors) for maybe just under $2gs total. Granted, you could only go to maybe like 2 psi on the stock fuel system. But it really depends on who does your exhuast work.
Eclipses, RX-7s, and Supras all have turbo models.