Low price merchant friendly payment gateway

Without getting into too much detail, we need to lot of transfer of large amounts upto $1000. However that's not our revenue.

We need a payment gateway which offers low fees ACH transfers, preferable below $0.50 per transactions. Do you have any recommendations?

Have you looked at Braintree Payments?

Maybe Fee Fighters can find something for you.

If you don't have a merchant account or are OK with dumping your current one, you can go with Stripe. They integrate the gateway and the merchant account into one and essentially just expose it with an API. I use it for a product and it is really good. Their pricing is pretty good,(no flat rate, 2.9% of volume + $0.30 per transaction if I remember correctly).I don't know how they handle large transfers, however.