1994 Maxima

I want to buy a '94 Maxima - 115 000 miles, (school car) for my son. The body and the interior are in a very good condition and the car runs good. After driving about 30 min., the "Check Engine" turned ON so I took it at the mechanic. He put it on scanner and found 3 error codes:
1. Knock sensor code
2. Mass air flow sensor code
3. Injector driver
The buyer asks for $2100 but after seeing what the mechanic found he dropped the price to $1600.
Should I buy it?
Appreciate your advice.

- The price for pure engines: VG30E 160hp is lots cheaper that VE30DE 190hp. Which one is in it? See link below for VG... VG is simpler and thus more cheaper to keep runnin.
- compare car prices on your area

Those 'lottery' codes may show just anythin; buying ol car is always 'risky', Check Engine light may start 'anytime' at that mile-age.
- MAF 200$ or more,
- KS may be bypassed (replacement job may be time consuming =costly in VE. Some shops have own tool for fast replacement, no need to remove lots stuff around.),
- Injector driver =ECU from junkyard 150$ or more.