I have a 1996 Maxima with 115K miles. I bought it used with 75K miles 2.5 years ago for $9.5K at a dealer auction.
It was a great price for a car that was loaded with bose, leather, sunroof, etc.
Problems so far:
Both rear window regulators slipped off the track. Replaced one, fixed other one myself. I think it's faulty design for just some of the cars that year, because a little plastic part broke in the same place on both windows.
Starter replaced.
CV joints replaced.
Oil pressure switch replaced.
Had rear evap canister light on. Disassembled and cleaned evap canister, light went away.
I am probably forgetting some minor things, but I don't think there is more than $1K in replacement parts/labor there. I budgeted $2K in expected repairs in my bid when I bought this car at the auction, so I am not disappointed.
I have a Hayes repair manual for minor things, and a fellow user from Maxima.org who is a mechanic, and does more serious work on my car on the weekends for half the price of a shop.
I have a custom intake, and some suspension mods: rear sway bar, and front strut tower brace. I also put in a modded valvebody, but sold it, cus It's a too jerky, and replaced with OEM.
If you are concerned about auto transmission failures you have some options:
Get a manual tranny. I wish I did that, but I can't drive stick, and I bought the car in a hurry

Get a transmission cooler. (hayden ones are $30 at pep boys, and take under 1 hour to install with very basic tools) That's what I ended up doing. A good insurance policy.
Maxima 4 speed auto is not as smooth as Camry's, some of it having to do with the torque the VQ puts down, but I wouldn't say it's unreliable.
So far, so good.