I've found these non polarity bulbs, they don't ship to the UK though and not canbus http://item.mobileweb.ebay.co.uk/viewitem?itemId=251084234877
They will have a polarity sensing/switching circuit built in,which gets round the issue of leds only working one way round and which would explain the high cost and why they won't be compatible with can bus
I should have guessed you would have found something like this that nearly proved my led statement wrong, I guess I should have been more specific in my statement lol