When it comes to quality the price is usally high.
A good seymour duncan would be about R800, that is cheap if think about it?
Since you have a really high gain Bridge pickup that is a seymour duncan, i would advise you to get another seymour duncan for the bridge postion(You cant mix apples and pears).
I would recommend the "Jazz SH-2 pickup", i heard it in a death metal setup before and it really kicks ass!!!
A lot of Metal guitar players use this pickup for the neck position.
http://www.seymourduncan.com/products/electric/humbucker/progressive/sh2_jazz_model/