whats a good turbo kit for a stock 96 ls?
and how much would it cost?

 

There are many different turbos/trims/sizes that change a lot in spool time and how it spools.
What is the car going to be used for? Daily or track?

Few examples that come to my mind are the most popular t3/t04 hybrid turbo. 0.63 a/r with 54 or 57 trim compressor wheel. 54 trim will give you boost quicker but down the line 57 trim will be able to provide more power and hold it for longer.
Less popular between hondas yet also very good turbo is a GT2871rs. Though I've heard of people using bigger GT30 series and even GT32 on a b16.
Will the motor be built or will you limit yourself to stock internal.

Prices vary, whether you buy a full kit or piece together a kit with your preferred parts. Only thing I would suggest is not cheaping out on any parts. Things like bov or wastegate must work flawlessly or you will face damage to the compressor/turbine and the engine itself. Yet parts like piping for air shouldn't be overlooked. Its preferred by many people that the pipes get welded to prevent any potential boost leaks. The cheap ebay pipes are very hard to weld because of the poor quality of metal used to manufacture them. I would honestly not use any of the cheap ebay parts. Even the silicone couplers tend to give at 10+psi. Buy it once and do not regret it later.

A used kit can cost you anywhere from 800$ to 1500$. A brand new kit can cost from 1800$ to well that's indefined. Also you should know that most or well almost every single kit is really not a complete kit. Does not include fuel pump/injectors/software and sometimes oil/coolant lines.

Also last point, make sure you have a proper pcv system because with turbo you will get some more blowby and you want to eliminate any potential unnecessary stress on rings. So eliminating your stock pcv system and making a custom oil catch can setup is highly recommended yet often overlooked.