if you can properly set up a turbo on your jeep for under $400, that will be extremely impressive.
have you ever done anything like this before? just curious, cause if you have, you will know its gona cost you more then $400 even with a junk yard turbo. tuning alone is going to be costly, not to mention any fabrication that needs to be done, the upgrades you will need to make to support the extra power levels(the standard ax5 transmission will most likely not last.) adding forced induction to an engine is no simple task even with a kit designed for that engine. building your own is another level all together.