I now have another offer - besides Köster - available. The door is from HDE and costs about €1,500 more in comparable equipment (profile thickness even 2 cm less) than the door from Köster - so about €6,500 (excluding installation!). I think that is quite good for a "simple" front door - so without side elements etc. - in approximately 110 cm x 210 cm. The fingerprint scanner is from ekey. The advantage of this door is supposed to be the more flexible further upgrade options with camera function and remote opening etc. Unfortunately, I have no information as to whether the additional cost is also (again) noticeable in quality. Ultimately, however, I think the price overshoots the target, meaning reasonableness, somewhat, especially since full control over possible later upgrade options will very likely not be utilized.