[m_km]

Your best choice would be Dwolla - https://www.dwolla.com/pricing/

You probably might want to start with the 0.5% Pay as You Go plan and as you go bigger, you can switch to a fixed-fee model. Once you switch to the other plans, you will be paying a flat ~$1 per transfer (both sending and receiving).

Handling fraud and chargebacks for ACH is more complicated compared to processing payments via cards. You probably should look into this before going live.

Source - Have built payment flows with ACH and cards for multiple marketplaces. Not associated with Dwolla at all. Just a happy customer.

EDIT:

Alternatives (that I have not tried) are Synapse - https://synapsefi.com/ach and Finix https://www.finixpayments.com/

[apelin]

Thanks for this. Thinking about Dwolla, but their onboarding time for Pay as You Go is 60-90 days.....

[m_km]

This ‘on boarding’ process - does it have something to do with Compliance?

[apelin]

Yes, it's their application review time.

[bpmilne]

Shouldn’t take that long. Drop me a line at b at dwolla.com if you go this route. Happy to assist.

[apelin]

I appreciate it, will do! P.S. great to see you here B ;)