Any reputable AC charger with an output of 12-40V that can supply 120W with a DC7909 barrel connector should work. Bluetti does sell the T200 on eBay which outputs 25.2V, at up to 8A (of which your AC50S will only need around 5A) You can also purchase the Bluetti Car Charging Cable on Amazon for $10. It's the same one as for the EB3A.

I can't comment on the AC charge you linked from eBay because it's a no-name brand adapter which doesn't disclose the output voltage or current - so buy at your own risk.