Chenna Erik,
Maybe you should try some of the book-sellers that hawk their wares through Amazon.com "new & used" (the Amazon Marketplace). Just search for 2300AD books or whatever via Amazon - sure as they are out of print Amazon have none but the entries are all there. Just click on the "new & used" link to find those that are availble. I've brought heaps of books of these various companies who are mostly US local town and suburban booksellers. They are totally professional and you can get some great bargins...
For example right now you can get:
Colonial Atlas (2300AD role playing game)
by Rob Caswell, Steve Venters
Edition: Paperback
Price: $15.95
Condition: New
Seller: intergalactic (Safe buying guarantee)
Rating: 4.6 stars over the past twelve months (157 ratings). Seller has 2084 lifetime ratings
Availability: Usually ships in 1-2 business days; Ships from FL, United States
See shipping rates
Comments: 1987 Games Design Workshop 2300 AD Sci-Fi Gaming Module (D9342-MH)
Many of these sellars don't ship overseas until you actually email them and they realise that Amazon.com charges enough to cover basic US Post for overseas shipping (taking a book about 2 weeks to get to Australia). The cost of international shipping is another US$ 9.79 per book. Much better than eBay.
PS I thought your Saschen model was pretty cool - I liked the Tornado green skin as well.