I have a 1998 Navigator I'm very proud of. I purchased it in 2001 with 68,000 miles on it for $24k. I am still thrilled with the car.
I had a vaccume leak shortly after purchasing it that was difficult to find but a 50 cent piece of tubing fixed it. At 150,000 I replaced the alternator ($175). At 185,000 #4 coil got replaced ($58). In early 2008, at 234,000 shift solenoid 2 (SS2) would stop working when warm and leave me with only 1st, 4th and a manual 2nd gear, so I replaced the solenoid body ($285) and of course new fluid and filter ~($85). These are parts only prices and I do ALL the maintenance on this car my self. The only upgrades of any kind the car has is a K&N filter since about 75,000 and I use the Lucas additive on every oil change since about 100,000. Oh yea, the brake light switch (on the pedal) had a wire broke off once too, but that was a freebie since I just re-crimped it.
In early December 2008 after returning from a 1200 mile round trip to tow home a 2400 lb Christmas present (241,900 on the OD now), I noticed the left rear axle seal was leaking which explained why my emergency brake had been getting weaker lately. Axle seals are cheap, but the car still runs so well I decided to give it a whole new refresh underneath. I purchased about $750 worth of suspension, wheel and brake parts, (shocks, urethane bushings, rotors, front calipers, front hubs/bearings, ball joints, front brake lines). Took me two weeks of weekends and evenings but I just put it back on the road this morning. WOW! drives like a new one. No more squeeky joints and rattling shocks.
Anyway, I guess I'm saying if go for it. This car is the best one I've ever had!