I'm looking for nice looking BT shaped lamps as they are not common here in Germany.
It would be okay if they do not work, because I probably can't run them here on 240V.
If I can get a working BT shaped lamp and gear for 110V I will find a way to run them here (like 12v to 110v true sine wave inverter or UPS with 110V true sine wave output)

You can still find them fairly often on the US eBay. If you look in the Web Finds board, members will often share any good eBay listings on that board.

As for the gear you have a few options for the US specific wattages like 100w and 175w. 100w MV lamps should run pretty close to spec using European 70w SON gear and the 175w lamps should run close to spec using European 150w SON gear. For both remove the ignitors. 277v 60hz US gear may also work directly on 240v 50Hz too and that voltage is common in a lot of US multi tap ballasts.