If orignals can be repaiured , i'd prefer to repair them , just make sure they get repaired professionally .
to be very honest spending 9k on just vents doesnt seem like a good idea to me .
i'll prefer to install the 900-1200 ones 8-9 times
The difference between the two will be in a sense that the after market ones if not of good quality will break down early , but they doesnt if you dont play with the ac vents all the time . i have no idea about the karachi market about repairing etc. someone from karachi may help if he got the vents repaired