My opinion. From experience and a R30 k bill. Do not do it. Rather take that money to the casino and gamble it out there. you will have better odds.
If you however do decide to do it. Be careful.
I just think if you had it from KM1 yes then do it. But with high millage on it is a HUGE risk.
Unless you are a mechanic and can do the repairs yourself.
There are High millage 320d' s here but some guys have had them from low millage and looked after them. You have know idea on how the car was driven and even then if you do replace something , like the turbo, there is still no guarantee.
I replaced mine brand new and it lasted 16 000km. Yes I could have replaced it again as it carried a factory guarantee, but i did not have a nother 5k to have the job done. I did not have a nother car to use while repair was done.
If it is just for work and back yes it is possible to negate the risk but I think it is still a no no.
I will buy one again but it will be out of the box or still under MP. and you can get those for around 140k.
What ever you decide
Good luck.
Turbo = R9000 excluding fitment (fitment around R3000)
Injectors = R8000 excluding fitment
Rear diesel Pump R5000 excluding fitment
Clutch = R6000 including fitment
You dont want to know the cost of the front pump.
The main issue is there there is no space so everything on the 320d is a Royal pain to get to.
This is just to give you an idea if things go wrong what to expect to pay to replace.
Mine cost me 30k, aftermarket insurance paid 13k.
Sad thing is I had a perfect 318 A/T station wagon (Gopher :argh

payed off. She had 200k on the clock and going strong.
But no, More power. I was a idiot.