go on ebay and look up IHI turbos, they make great turbos for small engines. As far as the intake plenum not holding boost I don't see why it wouldn't and I haven't had any problems out of mine yet.
With a cheapie kit you will end up spending around $1300 and get maybe 30 horsepower more out of the engine keeping it daily drivable, maybe more if you wanted to push the engine.
With a good kit you could really start to open the 4afe up, you would need turbo, manifold, intercooler, fuel pump, fuel pressure regulator, injectors, and I would recommend water injection, and then some way to tune that isnt a SAFC or SAFC2. The tuning is key to keeping a small displacement NA-t engine alive. Go with a greddy e-manage with ignition harness and injection harness, or go look up a perfect power SMT-6 or -7 unit which will do everything the emanage can do and more.
I cant really give you a price estimate, but its not just about cost, don't expect to be able to slap a turbo on your daily driver and go in a day.