I'm in the same boat. I love my 135i but the only thing that is killing me is missing the sport seats.
I've looked into aftermarket solutions but the only one I really seem to like are the Recaro Sportsters as stated above except they are way out of my price range.
Ill follow this thread in hopes someone has some lying around taupe leatherette manual sport seats.
Not trying to thread crap, hopefully you have another interior color. :]