In the 88xxx region, there is a window manufacturer who advertises with "amateurish," referring to colored plastic windows. Fensterbau Bräuer Schwendi. Apparently, they also use GEALAN.
As far as I know, it also depends on which material is mainly sold/installed among window manufacturers. This results in different purchase margins. In the region, we have few large window manufacturers who exclusively install/sell wood-aluminum windows. The conditions there are said to be better than those of a "normal" window manufacturer who sells 80% plastic, 15% wood/aluminum, and 5% aluminum. But: price is not everything. Especially with today's window prices, I would like to talk to references first (due to our negative plastic experience).