If anyone has reasonably extensive experience with comparable Agilent and Tektronix systems, it would be good hear their opinions.
It seems to me that your primary problem is the shipping cost, US to Australia. Which I can make a useful suggestion about.
I bought a Tektronix TLA 721 mainframe, with control module, no other modules.
It was listed US $629.95, seller kindly dropped to US $375 when I asked nicely. ALWAYS ask, even if there is no 'make an offer' on the listing. Especially with high volume sellers. They often just want to move it.
Then I had it shipped to Oz via a reshipper in the US.
http://www.shipito.com Who I can't recommend enough!
I'd been using them for a while by then, so knew the drill. They're very good, and obtain a huge discount from the international freight companies due to the large volume they ship. But I'd suggest you try a few lower value items via them before you do a big expensive item.
Anyway, the shipping costs were:
About US $90 to ship UPS ground from the seller (I forget the state) to the reshipper in CA.
Box was 71 lbs, 67 x 67 x 67 cm
Freight quotes were:
$470 via TNT
$341 via fedex economy.
I chose Fedex, but that was a BIG mistake, that I won't make again. I'd rather have paid the extra $130, to not get screwed around by Fedex. It was the first time I'd seen them quote less than TNT, who are invariably excellent.
Anyway, it did get here undamaged. Best of all, one reason the seller dropped the price was he didn't know the Win2000 logon password. It turned out to be nothing, just press enter!
(It took me a while before I thought of trying that, ha ha.)
Modules, probes and original manuals are easy. There are always lots of choices, and sometimes some very cheap ones.
Shipito have a freight cost estimator on their home page, so you can work out roughly what things will cost to bring to Oz, before you buy. Which means you can put the extra cash into the quality of equipment. (Or in my case, just be able to afford something at all.)