Mikey is correct. It is much more expensive to add options as dealerfit rather than ordering from the factory.
The OBC has a button on the indicator stalk and costs £100 as a factory fitted option. The MINI retrofit kit costs £130 and probably a couple of hours of labour at main dealer prices.
The MFSW costs £430 excluding fitting.
There is just one moon and one golden sun; And a smile mean friendship to ev'ryone; Through the mountains divide, and the oceans are wide; It's a small world after all.