Anything that drives and runs is a good buy for $960. Back then they had a lot less plastic crap on the engine and less complex electronics, but it's still 27 years old. Don't pour a lot of money into it.

For a daily driver, it was not a good purchase.  As a weekend toy or project car and you are very determined/motivated to learn how to work on BMW vehicles, do all the work yourself, know where to source parts, and have many thousands of dollars stockpiled for repairs, then why not?  

I think the cost of repairs will quickly outpace the value of the vehicle

Just keep in mind that parts are expensive for these old BMW vehicles and will become harder to find as they age. I see this with the old Mercedes we have in our house and can't get the owner to give up on it; have to look many places for parts and pretty expensive. And all this is if you do the work yourself and just have to buy parts. $960 is nothing so drive it until it dies, but if it's your only car definitely start looking for something reliable. And don't spend much on the BMW unless it's something very cheap and minor.