JD, good EU mfgers (who have shops) i know of, are:
Aquacomputer (CuPlex & TwinPlex series, AquaTube reservoir, i have some of their products):
http://www.aquacomputer.de/
OCPC UK (home of the Atlantis - owner is JessFM he's member of these forums):
http://overclockedpc.co.uk/
Innovatek (pHaestus' stuff):
http://innovatek.de/
Cooling Solutions (K4 waterblock, they have new blocks now):
http://www.cooling-solutions.de/
Low-noise
http://www.low-noise.de
And of course Zytrahus with his wonder Zytrablock (see the thread 'WB made in France' in Cooling News).
Now the ones i haven't been in relation with (try their 'wasserkhulung' section):
http://www.com-tra.de/
http://www.overclockingcard.de/
http://www.pc-cooling.de/
In the US there's also Cool Technica
http://www.cooltechnica.com/
Becooling
http://www.aquastealth.com/
OCH:
http://www.overclockershideout.com/