If you own a M9/92F/96F series or a PX4 Beretta model, a good resource is match shooter/pistolsmith; David Olhasso:
www.olhasso.com .
His site has many parts, services, etc.
I always liked the D line. I owned a PX4 C format 9x19mm & 2 96D series pistols.
I may buy a NIB PX4 D model .40 soon.
ClydeFrog