Re: How hard to find a Sport Package 328i?
A CPO 2007 Black 328i sedan with MT & ZHP is listed at Bill Dodge BMW in Westbrook Maine on the BMWNA website.
(I didn't search for coupes, xi models or convertibles.)
Since you indicate you want used or new, have you considered ordering exactly the car you want? As my last 4 BMWs have had SP and MT, I've ordered all 4 and been very satified - even with the 30~60 day wait.