Some people may not see eye to eye on this But For 300-400 You can do a lot, Just gotta be resourceful. Craigslist and Ebay can be your best friends . If you read around there are a lot of people making good numbers on 300zx turbo ECU/MAF
You could buy :
ebay/craiglist/volvo/startion/evo/junkyard intercooler($25-100)
manual boost controller $10-20
Auto zone specter intake($30-40)
convert to a 300zx turbo ecu($100-150).
Inter cooler piping $35-100 (You could have a muffler shop make u intercooler pipe for cheap, Heavy but cheap and easy to access.
Total at high price: $435
Low price:200
That's if u do the work yourself and source the parts cheaper.If u find the stuff the cheaper route u could even get a turbo back crushed exhaust For around 200.
Just shop around my best advice.
Here is the ecu swap
http://forums.hybridz.org/index.php/topic/26230-z31300zx-ecumaf-to-280zxt-swap-guide/page__st__20