Buying things from Germany is sometimes surprisingly cheap and quick. However if the goods are faulty then there is often a language problem and a large cost to ship them back to get a refund.
China is actually reliable and reasonably fast - although I only buy very cheap items as I'm unsure about when HMRC starts to charge duties. Some Chinese suppliers seem to have warehouses in the UK fronted by several sellers' names. These charge a higher price - but they do not have any provision for returning faulty items. At best they will give a full refund - otherwise you have a Carch-22 loss.
In my experience Amazon.uk have been unconcerned about Marketplace Partners hiding the fact that items will come from the USA with all the Customs liabilities.