I know that going directly on to the German eBay also helps find parts/plans that might not always be aware of. If you type ‘bauplan’ you will often find plans/drawings, expanding on this ‘modelbau’ means modelling and if you are interested and in warships the easiest terms to use are ‘schiffe’, ‘panzerschiffe’, and ‘kreigschiffe’ which will translate as ship, armoured ship, and warship respectively.
It does help that I have two mates who speak fluent German to help with more specialised terminology. I have bought plane from German eBay and they are remarkably good, just in metric scales (1/100, 1/50, 1/25) but is easily convertible to our scales.