I think in the US I’ve heard ETF/ACH transaction fees are usually around $2.50? It might be possible to have that apply across a batch, though, as in if you submit 10 payments to 10 different people as a single transaction it’s still just $2.50, or 25¢ per person. I’m only getting this from hearing accountants complain at companies I’ve worked with, so I don’t understand the details. But I’ve seen it pretty common with companies doing payouts to want to see a minimum amount before they actually send the payment, otherwise it’s not worth doing.