Not sure how much you need to spend, but here are a few common W123 PM items:

Fuel primer pump
Glow plugs
Glow plug fuse
Power steering filter
Coolant bottle cap
Vacuum connectors (3-way & 4-way)
Radiator hoses
Coolant bottle hoses (2)
Transmission cooler hoses
Flex discs
Idler arm bushing
Brake pads
Brake fluid
Sway bar links
Oil cap gasket
Fuel cap gasket
Fitted fuel hose at tank
Engine compartment fuel hoses
Front crankshaft seal & spacer
Oil filter o-rings (2)
Air filter mounts (3)
Air filter bracket
Breather hose (new style)
Transmission shifter bushings
Drive belts