> - what model did you buy for 50€ ? was it second hand?

No, it was new. A "Pantum P2500W". However, it's from a retailer (iBOOD) known for buying surplus/overstock/special-purchase items from the US and UK market (at reduced prices), and reselling it in the EU. I would imagine the prices to be slightly lower there than in typical big-box stores, but I have simply never seen the brand in any physical store, so can't really compare it obviously.

  > any estimate on how many regular text page can you print with your 20€ cartridge?

According to the toner manufacturer, it's 1600 pages. And generally, all toner cartridges that come up when entering "P2500W" into Amazon suggest 1600 pages. I don't print that much that I can verify it; with just the occasional shipping label every couple weeks I would last quite a number of years if that was correct.

  > any links to buy the printer/cartridge

For the cartridges, I see a plethora of options when entering "P2500W" into Amazon.de, the majority of which are between 19€ - 23€, 4.5 to 5 stars, all of them mention 1600 pages.

Regarding the printer itself, I don't have a good recommendation. iBOOD (where I bought it) does not sell it anymore (iBOOD mostly sells a quantity-limited amount of surplus/overstock/special-purchase items, and it was in September 2023, so there for sure is no stock anymore). When looking at the price graph of a popular price aggregation site (https://geizhals.eu/pantum-p2500w-a1474488.html), I can see that the price started out at 55€ in July 2016, the lowest price a store was selling it for was 35€ in 2017 for a month. Then it was available for 50€ a couple of times for a few weeks - months per year, and otherwise out of stock; until it seems to now be sold at Amazon.de by a third-party seller from China (without going out of stock constantly) for reliable 90€-110€ (this very second for 109,90€).