PEI bed are 20€, not 100€.
Just buy a compatible one on amazon or elsewhere.
You just need to have the bed size somewhat correct, and the magnetic base have a sticky surface that will adhere on whatever is below your glass bed (usually some metal structure to hold the glass)

I’m starting to build a voron trident on it.
For now I stripped everything and only have the base frame.

tronxy x5sa-400

Ah you too decided to torture this printer.