I've been tracking this bad boy for a few months now and I've finally come up trumps but I thought I'd share a couple avenues that are open still. I'm based in the UK but these tips are probably useful elsewhere as well.
1) Buy a foreign language edition and upgrade the cards with the Dust Tactics Unit Upgrade Pack. It's the models you're after anyhow and even the English-language edition is going to have those old numbers on them. For example, Amazon France have copies from 98 euros. Sure, you'll have to pay for delivery but certainly if you're in the EU, that will be minimal and without import duty.
2) Have faith in the "Notify me when back in stock" buttons. This is actually how I just picked up a copy from The Book Depository for £46 with free delivery. I thought what's the use if it's out of print but on a whim I put my email down and a single copy came back in stock and at a huge discount as well! I don't know if it was a return or simply a dusty copy that got lost somewhere in the warehouse but it just goes to show it's worth a punt.
Hope that helps!
EDIT: If anyone's interested in the EU, The Book Depository on Amazon UK have another copy for £62.86 (only 1 in stock) though a bit of warning: this may be a mistake as on The Book Depository site, it's listed as out of stock.