I am looking at getting some polyurethane rear sub-frame bushes made up for my car, unfortunately the unit cost is quite high due to tooling costs but if other people are interested this will bring the unit cost right down. The bushes will be manufactured by a reputable polyurethane molding and manufacturing company. They will cost between R300 and R400 per bush (i.e. R1200 to R1600 for a set) depending on how many people are keen.
The bush will consist of 4 parts: the two polyurethane bushings, the sleeve and a thick washer as shown below:
The assembled bush looks like this:
Let me know if you are interested and feel free to ask me if you want any more info.