Some things I should pick up from digikey:

Terminal Blocks – Headers, Plugs and Sockets : Choose connectors for circuits.

Rectangular – Headers, Male Pins
Rectangular – Headers, Receptacles, Female Sockets :These are really what I’m looking for.

Capacitor kits : expensive

Wire Jumper Kit

DB9 connector shell

DB9 male , DB9 female : though still need to decide where the connenctors will sit on both the stepper as well as the control box. I imagine the interconnect cable will be male-female

Low voltage op-amps : NJU7016D-ND 1v-5.5v 2 op-amp circuits, NJU7051D-ND 1-16v, 1 op-amp circuit,  NJM13404D-ND 2-14v, dual op-amp circuits

DC-DC voltage regulators, low voltage: MAX756CPA+-ND input .7-5.5v output 3v, 5v,

Look in the DC DC Non-Isolated – Point of Load (POL)  family of products for complete units for DC -DC regulation.