For Europe, ebay.de or even ebay.fr has ton of used test equipment, and it is not much more expensive than ebay US.
Especially if you take into account shipping.
For even cheaper, you should check your local equivalent of "craiglist", in France, it's leboncoin.fr (they may ship to Belgium).
It's usually here that you can have the best deals. They're not professional sellers, sometimes just people that don't even know what they are selling.
As for global shipping of ebay.com, it does work very well and the prices are reasonnable, and all custom taxes are taken care of.
I've never had problem.
Of course, it can be cheaper going directly through USPS, but it's slower, and with some luck, the custom may not charge tax on the package.