eBay is probably your best bet. Looks like there are a few on there for around $150ish that claim to be for an r52/3. I've never seen one of these in a MINi. Does it go in the boot? If so, I'd hate to give up the space in my cabrio. It's already barely large enough for a few bags of groceries. Is there a factory run cable already back there?
Have you considered a Bluetooth upgrade? The guy I bought my cabrio from installed it in my car. They are cheap and plug-and-play. Phone or iPod connects automatically and you stream music....and also have hands free phone if you wish to use it (I dont). Mine works flawlessly. I suppose I'm assuming you have an iPod or smartphone, though....
