Ridiculous prices. On my X3, they're charging R23k for time alone (covering you for an additional year or 100'000km). Then it's R33k to add just 5000km i.e. 1 year of 105'000km.
I honestly feel that with the N55 engine (I've had 2 m135i's in the past), they're solid and will not give issues (unless heavily modded!). With my X3, which is a 2.0d, I'm leaning towards not extending, and just taking out an extended warranty (after-market). With regular servicing, this may work out cheaper (hopefully haha!).
Good luck