The price of ACH debits is 1% + 30¢, _capped_ at $5. So a $10 debit would cost you 40¢. I know you've said you're doing high-dollar transactions, just wanted to make sure that it was super clear, as we try to be with all of our pricing.
Some other people just simply don't understand how _quickly_ they can get money via ACH. It's a matter of venturing into the unknown vs. what's tried and true. So when we say "You'll get your money today, in your bank account, if you use Wells Fargo, and tomorrow otherwise," they say "really?" And decide ACH is good enough for the cost. Then again, that's on the payout side rather than the pay-in side, though I guess if your website accepted payment via check, it'd be much faster there, too.
There are also all kinds of other complications in dealing with paper checks that may make it worth the $5. Here's the issue where we talk about Balanced and paper checks, and this comment in particular is very insightful: https://github.com/balanced/balanced-api/issues/69#issuecomm... Checks are also not reversible, which we feel is a significant drawback.
Anyway, no matter what you do, feel free to ping me if you have any questions payments related: I've really enjoyed learning this domain, there's so many details, and they're all so important...
We actually just rolled out a new version of our API last week, and put a _significant_ amount of effort into improving the documentation. Check it out: https://docs.balancedpayments.com/1.1/overview/
Steve mentioned below that they have new docs, I have not had the chance to check them out yet.
I'm happy to give you access if you'd like to try it out -- just email me at amber@stripe.com.