Bhai, you heard absolutely right. The ECU costs Rs. 90K and is vulnerable to getting damaged due to water splashing.
You must have seen the yellow sticker in Urdu language inside the bonnet about this
Since you are in Abbotabad, I cannot suggest where to buy ... probably you will have to get it from Rawalpindi Saddar somewhere ... I got mine for Rs. 500 from a Toyota center in Lahore.