I was looking for a pair a while back and asked on X5 drivers - a few people suggested the Mont Blanc bars and I bought them - they do the job and are quite sturdy, take up to 100kg I think. Also have locking units to stop opportunistic theft. Will try to find the link and post it up for you, they were not expensive, around the £70 mark as I recall, while the OE ones were ridiculous - around £200.