I kept 2003 TZ G 3.4 Prado for 5 years from 2010-2015. I stopped driving my brand new Audi A4 because Prado was so unbelievably comfortable to drive. Its extremely reliable, drove on multiple off-road tracks, including for camping at Deosai Plains. It never gave up. The cool-box was especially amazing, kept drinks super chilled for long drives.
About air suspension: Believe me its not an issue, 2003 Prado's air suspension is not very complicated. It just has 2 rubber balloons near rear suspension, a compressor to fill the air, and a computer that keeps the car leveled at certain level regardless of how loaded the SUV is.
After aggressive off-road driving in north, one of its balloon leaked at 120,000 km. I wen't to Toyota Cantt Motors in Lahore and asked for balloon replacement, they said they don't have it, but will arrange in 1 day. I replaced both side balloons for 30,000 Rs. (Price will be higher now because of dollar hike).
Except air balloons, I did not replace a single major part. Drove it from 72,000 km to 165,000 km without any major issue. After buying it used I found out that its odometer was revered, so I am not really sure how much mileage it actually had. So you should be very careful about reversed meters. Don't fall for low mileage in old cars/SUV, its mostly a scam. The best way to detect mileage is engine start sound and drive feel. I test drove 2 Prado's and a LC, the one I bought had smoothest sound and acceleration response. So always test drive before buying.
That said, I sold my Prado in 2015 as a 12 years old SUV. If you buy it now, it will be 15 years old. Despite its reliability, 15 years is a big timeline for a vehicle. Its packed with electronic features, so there is more to go wrong the older it gets. You should expect high maintenance cost with such an old SUV with modern features.
90% of 3.4 TZ in market are 2002-2004 models with price tag of 4-5 million. I would never recommend anyone a 15 years old SUV for this price. I think it shouldn't be worth more than 2 million.
