w/o postage on ebay.de it's better to be 100+5% sure that it's faulty 
first of all your 300-400mV reading is for B18E engine so forget it. you should have used next step in fault finding workflow which requires LED
I'm not sure which Haynes book you've got - early one up to 1992 models or later one up to 1997 models but basically they have same workflow for ignition system checking. so if you've any of them use it
things you should check are:
1) flywheel sensor - check resistance is within tolerable range, should be clean, fitted properly (should fit only one way)
2) power supply/earth connection to ignition module.
3) ignition signal - that's where LED comes into play
4) ignition coil output/power supply signals.
if I understand wiring correctly, connectors on ignition module should be conneted to following locations:
* one 3 pin connector should have flywheel sensor/ignition signal/knock sensor connected to it
* another 3 pin connector has flywheel sensor/knock sensor/ground
* 2 pin connector has ECU signal/REV counter
just follow Haynes and you should be fine - it's fairly simple.
goodluck and hope this helps.
PS sorry for stupid question but what makes you think you've no spark? have you tested on HT lead with spark in it?
This car was a mistake 
