Rick, I bought mine from Hazet for ~20 euros I think.
Hazet #4466-2
There is no way I would try to change the plugs without the 12pt 14mm deep socket. Also buy your plugs from a dealer and not aftermarket. It will help to have a few long extensions handy as well.
135i Spark Plug replacement DIY...
http://www.1addicts.com/forums/showthread.php?t=602804