
Welcome to the-gauge Peter!
Trainworld has outstanding prices, quality and service, and they ship over the pond:
http://www.trainworld.com
I asked jus thte other day for shipping to England, and they said it's starting at $25. I immagine one loco would be $25 shipping. I hope they don't charge you high customs, mate. They carry more than what they list, if you want to order WS, track, etc. You can ask, and you will get a free catalog if you order.
If
http://www.1stpalcehobbies.com ships to Oz, they have decent prices on most things. Loco's are better priced at trainworld, but 1st place has it all. I quite buying from 1st palce only because I have to pay bloody sales tax because it's located in my state, so I just go to my LHS.
Another option, is my LHS, I think he charges full list price (he does for walk in), but he does ship anywhere, and he is very knowlegable. His web site is plain and simple, and offers only a little information
http://www.hawkinsrailservices.com/pages/1/index.htm Best to just e-mail Jack
jack@hawkinsrail.com or call.
When internet ordering, it's important to understand the backorder policy, as they may charge again for shipping. Most are reasonable and will do what you want with back orders, a few are unreasonable.
You may get some better ideas is you post what you are specifically after, including scale. The above work with all scales, but some are "better" at HO. I know the N scale guys have some sites they use that are scale specific.