Ignore Fox, the spoiler was one of the rare bargains you get on eBay and when you get it, you'll wonder why you ever considered paying 4 times more for one, just because it in a lovely BMW box.
Item number: 220918799878
If for some reason you hated it (honestly can't see why you would), chuck it on E90 post for £40 and someone probably will have it off you by the end of the day (especially if it's finished in silver or black).
Only piece of advice is to not use the tape that comes with it - go to B&Q and buy some No More Nails tape (red). Should be £2. This No More Nails tape is mental strong.