I'm cheap...I'd go source one out on ebay. Just make sure it's designed/rated for the right number of cells and chemistry(though your BMS will probably prevent over-charging...you still need
enough voltage). You can always change the plug on it to match your battery's charge port.
There's probably a 5a one out there. I bought a 5a 72v one a while back.
Quick search example:
https://www.ebay.com/itm/371918053640