Reliability, etc.

[Titan]

I'm looking into buying a 89-91 240sx soon and I have a general question about how reliable they are. Simply, what can I expect to need repairs if the car has approx. 170,000 km? I realize it differs by the condition of the car I am purchasing, but say it is in well mechanical condition. I was just wondering about what repairs I may have to do down the road, and how much will they cost me? I am only 17 and on a fairly tight budget, so this information could be very useful to me.

Secondly, I know when I purchase the car I should replace the plugs, plug wires, rotor, dis cap, anything else? Are these easy to replace? Is there a tutorial on how to do so? What other maintenance, other then oil and filter every 5000 km, should I perform? And how often should I perform them?

Thanks in advance.