Hey James... The injectors should be readily available off bimmerforums or E46fanatics from anyone who has supercharged their car (and therefore upgraded the injectors). Below is the cross-reference list off realoem. If you are anywhere near Dinan or VF Engineering in CA (too lazy to look at all three locations) they may have some take-offs from install jobs on customer cars. Otherwise a quick search on car-part.com should yield some breaker's yards that have them.

Good luck...

E39: Details on E39
E39 528i TOURING
E39 528i SEDAN
E39 525i SEDAN
E39 525i TOURING

E46: Details on E46
E46 323Ci COUPE
E46 323Ci CONVERTIBLE
E46 323i TOURING
E46 323i SEDAN
E46 328Ci COUPE
E46 328i SEDAN
E46 320i SEDAN
E46 325Ci COUPE
E46 325Ci CONVERTIBLE
E46 325i TOURING
E46 325i SEDAN
E46 325xi TOURING
E46 325xi SEDAN

E60: Details on E60
E60 525i SEDAN

E83: Details on E83
E83 X3 2.5i SUV

E85: Details on E85
E85 Z4 2.5i ROADSTER

Z3: Details on Z3
Z3 Z3 2.5 ROADSTER
Z3 Z3 2.8 ROADSTER
Z3 Z3 2.8 COUPE