I have been using Keepa for most of my Amazon.de orders lately and I am very satisfied with the results. Even though the interface is admittedly a mess, it works well for tracking the volatile pricing you are seeing right now. I have used it for several major household purchases and have no complaints about the data accuracy. The subscription is probably worth the cost if you are being methodical about your budget for a big gift. Honestly, just get any coffee machine from Sage, you cant go wrong with that brand for a wedding present. It is much more reliable than other trackers when you are on such a tight deadline tho... Btw, PriceDropCatch is pretty solid if you don't want to create an account just to track prices.

To add to the point above: unfortunately, the free polling rates are pretty disappointing. Honestly, just Google Amazon price tracker Reddit threads; theres a post explaining API latency and saving money without Keepa.

Regarding what #1 said about "I have been using Keepa for most of..." - honestly, I agree that it's the most robust tool for raw data even if it looks ancient. But you should be careful with those high-end espresso machines on the German site. I think I read somewhere that Amazon.de uses some weird regional pricing logic that can occasionally mess with the trackers. Not sure but I recall someone saying Idealo actually pings more frequently for the German market specifically. Might be worth keeping a tab open there too just in case Keepa misses a lightning deal... those things move so fast. Make sure to look at the Price Trend feature if you can find it. IIRC it shows the lowest price across all German retailers, not just Amazon. Just a heads up, the wedding is coming up fast so dont hold out too long for a 5 euro difference if the stock starts looking low.