For those who want a 300m3/h class machine that's energy saving and presumably quiet and have multiple speed control, i think you can try the Lotte LE-901. DHL safe too. Filter sgd 65, stock up or not up to you. Can go for cheaper option like the rmb25 or 40 commoner TB options (no need to alww, just place order)...up to you. They will work.
Dont only place your hopes on carousell/gumtree esp the BNIB cheap one which come like a few times a year and v limited sets. I think a lot of people are aiming also for the next 6 months.
Besides, you wanna customise filter, also need 30 dollars odd per piece at least.
Can spend that few more tens of dollars to get a brand new one. Heck most second hand ones arent cheap also.
LE-901 also can adjust the sensor sensitivity, so that the Auto mode can be tuned.
Just some thoughts.
Class 2 for energy/airflow efficiency. Same as LG LA-Q379SB/PS-R459 and Samsung AX40