New rotor discovered for narrow hubs in 324x22, same size as OEM 135i !!!
Along side the e91 Perf rotor 34216795755 there is/was a Blank face rotor for 130i !!
Its part number is
34216787931 , and it gets better because ZIMMERMAN made a copy as part # Zimmermann 150.3477.20 or 150347720
EDIT: Maybe even ZIMMERMANN 150.3477.00
EDIT 2: ZIMMERMANN 150.3477.52 should be their slotted/dimpled version of 34216795755
More alternate part numbers for this from OEM's
http://www.findpart.org/part/bmw-34216787931/
http://www.autopartoo.com/oem/248078.html
My Guess is that it costs under $150 USD/side which is about the current ECS cost of the e91 EuroPerf rotor. Interestingly, perhaps because of exchange rats, the e91 rotors cost about $50 less today then they did when I made this article.
Problem will be sourcing these, they are rare or have expensive shipping.
Sources:
http://www.bmwfaq.com/threads/frenos.553788/page-4