For those that have purchased on either Amazon.de or Amazon.jp what is the trick? Do you use your existing Amazon account or do you have to set up a new account??
I was just going to suggest adding an asterisk to Amazon to account for the UK, Germany and Japan sites. Overall, I love the Amazon int'l options since it gives me access to tools I either couldn't get in the US or could get but at a significantly higher price from a local seller.
So the other poster above answered some of the questions, but I'll add a bit more. Use your US email to log into UK and Germany. It's the same account/password, but used on different sites. But lately, I've seen Amazon offering the same items on the US site and indicating it was a "Global" something or the other eligible which means it's coming from overseas. So you may not need to log into the UK and Germany sites anymore? Or maybe I'm only seeing that because I've logged into both sites using my US Amazon account? Regardless, if the item is purchased from Amazon (the seller), they will handle all the customs and duties (duties are covered in their shipping quote when you checkout) and they do remove VAT tax when shipping to the US. Free prime shipping is not an option for any int'l order. Delivery can be 1-3 weeks. The carrier is usually some discount carrier, there will be little visibility into the status of the order once it leaves a European port. Just falls into a black hole until it shows up. More often than not the package will be damaged or destroyed and packing material is marginal at best (what we are used to with Amazon, except they use the kind of cheap cardboard you find in Harbor Freight stores - thin and tears easy). If it's not too expensive, choose one of the expedited shipping options from UK and Germany, your results might be better? Ordering anything valuable or subject to damage would be dicey in my experience, though I would expect Amazon to handle it well if you needed to get a replacement item.
Amazon Japan has different rules and you have to create a new account on their website. Searching for things on the japan site is problematic. Usually if you have the model number, I've found the product, otherwise it's hit or miss with Amazon's translation of your search text and their products. Orders can only be placed on the Amazon Japan website for their products. The shipping can be a little more expensive (but I'm on the east coast) to the US. I recall my last order was 2 socket wrenches (3/8"), 2 socket rail sets, 3 extensions and a few lightweight knick knacks mixed in. So maybe 7 lbs total? That was $30+ in shipping. But, delivery was 3-4 days flat to my door using EMS. If you've never used EMS before, they are flat out fast and good! The cardboard box was thick and well-taped, contents stretch wrapped with care to a cardboard backer so they wouldn't rattle or fall out if the box was compromised. Frankly I was astonished! The only niggle is I think I had to sign for the delivery since it came via EMS. And if you're not home, you may have to pick it up at the local post office (they use USPS for local delivery).
Lastly, try to be aware of different names for tools in different countries. It helps when searching the regional Amazon sites. For example, wrench vs. spanner on the German site. Spanner will net you more results. But if you have a model number, that eliminates this obstacle.