@grillchen @kaia I do use Recyclingfabrik, a german / EU company. They're pretty reasonable with their pricing (22-24€ for rPLA and rPETG), and if you send in stuff you also get points based on usable weight that can be used for a discount. And really, if you can afford a printer you can also afford two closed bins for PLA and PETG…
By now pure PHA filament has also become affordable with ~25€ / 750g. Only true bioplastic that I know of.
Of course the best to do is to show resourceful humility.