For Amiga stuff difficult to find here in Europe , you can go there: http://www.compcity.nl/pc/index.htm,
this is an webshop located in Netherlands (spreak neederlands or English, so as you like
) and you can pay on a Belgium account or with others methods of payements (more details on the site).
They send you, if you ask it, a free paper catalog every 3 months or every news stuff.
They have a very good quantity of different Amiga stuff (hardware and software).
Other else, when i can find it here in Brussel, i go at: http://get.to/genamiga.
It is there where i have order the AmigaOS 3.9 cd-rom.
You can order through email too if you want (that is what i do always here) and you can ask info about stuff too if needed.
Hope this can help you.