I don't remember the exact numbers, but my gut feeling is that for a 300 euros product it would be a few euros. It's not separated in receipts or price tags or such. In any case when it was introduced years ago, the prices certainly didn't jump up by any really significant amount. The fee is already paid by the manufacturers (or importers if imported from outside of EU). That fee directly funds the system to collect and process the old devices, so it doesn't dangerously go through the state.