For comparison, an offer from us... also Brandenburg.
Plastic windows
Surface: white on both sides,
Triple thermal insulation glazing Ug 0.6
Roller shutter attachment elements (lawyers) with PVC armor
(alternative aluminum armor)
Belt drive
2-leaf mullion windows,
Turn / turn-tilt,
BLA 1510 x 1340 mm + lawyers
489.90 Euros net
1-leaf plastic windows,
Surface: white on both sides,
Double thermal insulation glazing
BLA 1010 x 1000 mm without lawyers
Garage
145.40 Euros net
Delivery and installation were extra... but in one total sum.
Therefore, I cannot give you the exact price per window.
But around 100 Euros per window should be about right.