If you're trying to piece together a "budget" kit with just the bare minimum to get you boosting, then you should focus your search on used parts, and possibly junkyard turbos off factory turbo cars. If you're trying to build a "custom" setup to fit your needs, you can end up spending as much or more than you would on a kit. Besides the main components(turbo, manifold, piping, wastegate, downpipe, oil feed/drain), you have to think about what kind of fuel management you want to run, and what kind of add-ons(BOV, I/C, gauges, boost controller, timer, etc) you think you'll need. For a low-buck setup running low boost, a 12:1 FMU and an inline pump would probably be the most cost-effective and would allow you to run boost on your stock injjectors. If you plan on running more than about 8lbs of boost, I would consider looking into better forms of fuel management.