My 21 year old son recently totaled his 98 Nissan Altima (his first accident). He soon starts fire school to become a certified firefighter. Needs a good car for back and forth to school (about 25 miles one way). But fire school was expensive and most of his and my cash was used to pay tuition. Son has found a 1995 BMW 325i convertible, 176,000 miles, for about $4,000 that he would like to buy. Top looks newer than car, but everything looks to be in good shape. Have not had the car looked at by my mechanic yet. Having never owned a BMW, I worry about cost of maintenance and future repairs. What do others suggest? Is this car going to be a money pit?
BMW’s are for people who don’t have to ask about cost of maintenance and repairs. If you have to ask, get a more reliable car. 
I agree, until he has a stable income he needs reliable, inexpensive transportation. This BMW is not likely to be that car. It’s hard enough to find a good reliable, economical car for $4000, much less a good BMW.
The e-36 is probably the last BMW that can be considered NOT to be in a group of cars that are overly complicated. They do have trouble with the convertible tops not folding correctly (along with just the normal stuff every car has). I can’t say it would be good for your son to take this car on when I also consider his main emphasis is going to be on training. Great car for a man on a budget if you can do the work yourself. These cars are not “money pits” in any sense but they do require mainteance. I certainly can understand why he wants this car as they are really fun to drive. A firefighter with a BMW convertible, he will have a great time when he is off work.
If a mechanic does check this car out make sure he looks the front ball joints over, the AC condensor, water pump impellers fall off, blower speed controlls and AC display can give trouble, rear shock mounts (upper) can get noisy, and as mentioned the convertible tops can get hard to fold correctly and the “zipped in” rear window frequently needs replaced.
Cars this old are rarely good commuters. I suggest that he put his money into a much newer car with half the mileage. No it won’t be as much fun, but it will be a more mature decision. As a former young man, I can understand the desire for a fun car at his age. But he should wait until he has a steady job and can afford one. I would stay away from Toyotas and Hondas. They are too popular and will cost a lot. Maybe a 2004 Chevy Cavalier LS or a 2003 Chevy Malibu (base model). He can drive the lump for a couple of years.
"A firefighter with a BMW convertible, he will have a great time when he is off work. "
You’re a psychologist, aren’t you 
No but I play one on the internet.
Spend $4k on a Hyundai Sonata for a sensible commuter car. If he really wants a convertible, get a Miata. I would run, not walk, from that BMW (and I’m a life-long BMW owner).