About a year ago I replaced my mudflaps for the same reasons as already mentioned before.
There is a company in Boksburg which was advertising PVC Truck Mudflaps.
They were 68 R excl. VAT each for a 450 x 600 mm Mudflap.
I had to cut the Mudflap to size, meaning that I got 2 pieces (LH + RH) out of one Mudflap for (68 R)
For the once which are interested:
Vast Consumer Integration:
011 383 3030