Nissan still make the parts of have them in stock at least, besides there are soo many wreckers out there with these cars in their yards that you wont have anything to worry about...
Some parts vary in price but as they all do... but the aftermarket scene for these cars and motors is unbeliveable, everything and anything you could want for a car (but all at a price)
If you don't want to overly modify your car and just do basic mods like Link said then you will get away with it cheaper... if your going for performance and highly modify the car then could cost you a pretty penny..
If your on a budget do basic mods and have fun wit it
Best car i've driven personally (havnt driven many tho lol)... fell in love with them straight away!
*sheds a tear*