Just like you, I was searching for budget friendly, simultaneous charging options (charging hubs). And yes, there are basically more or less exact copies of DJI's charging hub, even with additional screen in the middle, showing some battery data. After searching on various sites and reading about different opinions from people who bought them, I decided not to spend 25 - 35 € on those, but to find used, original DJI hub. That's what I did, and I can only recommend not to save money here, I have no idea what kind of circuitry is inside and what can that do to my batteries (as you know, those are not cheap).
You can find used original DJI hub for around 40 - 50 € (USD) online. I think that's acceptable, as it is original.