Links to OO (1/76th) scale bits and pieces found on t'interweb that may be of use for 1960s, maybe 1970s era NZR layouts.
These are of British prototypes, and most are exactly or very close to what we had here at the time. Others are close and can be adapted / hacked / modified to closely match our New Zealand flavour and style.
John Ayrey Die-casts Ltd. This is a wholesale outlet but has a really good on-line catalogue for viewing potentials including :
B-T Models - 1/76 scale Leyland, Thames Trader, and D-series Ford trucks, crates, barrels, pallets, loads.
Classix (Lots!) - 1/76 scale Morris Minors, Morris J1 vans, Ford Thames 300E vans, Ford MkI / MkII Consuls and Cortinas, 100E vans and cars, Austin A30s, A35s, and A40s vans and cars, Triumph Heralds (even a Vitesse!)
Exclusive First Editions - 1/76 scale great range of Bedford TKs, Thames Traders, oil drums, milk churns, wooden pallets, etc etc.
Oxford (Lots and lots!) - 1/76 scale Ford Anglias, Capris, Cortinas and Zephyrs Mks I, II, and III, Populars, Austin A40s, Princess(!), J2 vans, and Minis, Bedford Ambulance, CA vans and TK trucks, Commer Q25 and PB vans, Vauxhaul Crestas, Victas, and Vivas, Dennis RS, F8, and F106 fire engines, Bedford TK fire engines, Jaguar MkIIs, Landrover lots of Series Is, Morris 8s, Minors, Oxfords, and J1 vans, MGs, Rover P6s, Standard Vangards, Triumph 2.5s, various "pie cart" type trailers, Fordson tractors, VW.
Red scale Modelbau - 1/87 scale lots of loads like pipes and slabs.
Hornby Skale Autos
Availabilty seems a bit vague but a great selection including Bedford TK trucks and CA vans, Bedford Tk fire engine, Ford Anglias and Cortinas MksI and II, Ford Zephyer Mk III and Vauxhaul Cresta taxis, E-type Jag, Landrovers, tractors, Morris Minors inclding vans, Morris Oxford, Austin J2 vans, Standard Vanguard, Jaguars MkII, MkIV, and an XK120.
These aren't exactly budget(!) but worth a mention.
1/76 scale - there's a few Foden, Thornycroft, Ford D series, and Scammel trucks, a bit of farm gear, and miscellaneous items like oil drums and petrol pumps, various crowds and groups of people, and even a crazy or mini-golf course!
But my favourites are the OO scale Heavy plant & Road Machinery,
particularly these two Ruston Bucyrus 19-RB cranes - real ones
I remember seeing as a youngster :
Various detail etchings including Side chain hooks and eyes
Includes some older Bedford ML trucks and trailers
And some more found at the highly reccommended Hattons Store including vehicles, loads, and trackside bits:
Grandt Line -
all sorts of detail bits, a bit like Tichy products.
Mark's Model Works -
Specialises in CAD designed brass etching, for things like 4-wheel chassis, washing lines, birds.