A lot depends on your intended use and budget.
For a lower end track car like mine with low boost here:
https://www.redlinegti.com/forum/viewtopic.php?f=32&t=53425&p=502076&hilit=intercooler#p502076Stock motor comes with Forged conrods, Forged pistons, sutable Cams and Ecu
Used Exhaust manifold
$50 WRX turbo
Dump pipe
Oil lines
Old Intercooler and pvc piping
A rising rate FPR
Total cost about $800, and it's still running strong (needs new engine mounts & a CV)