rennspec website is down for maintenance - ghetoooooooo...
This is the reply I've gotten from a very reputable local shop:
Revised estimate attached, per physical inspection observations. Should the bumper require replacement, the price would increase by $435, including repair labor cost offset. A request for the price of the Euro bumper (51 11 8 043 958) has been sent to BMW AG, as one has not yet been sold in this market. The price will likely be comparable to the correct bumper. Additional parts may be required.