Alternative to Sprout for Tree Planting? Alternate API? SS Fees HIGH!

We really wanted to incorporate the Sprout extension, but the more I read, the more didn't make sense. Squarespace says it costs $0.50 per tree, but theGoodAPI says it's $0.33. I emailed them, and they explained Squarespace adds $0.15 cost per tree due to "partnership fees." So basically, that's a more than 45% markup on the cost to plant a tree. That's equal to the entire organization's operational costs for responsibly planting those trees! And no, Shopify doesn't do that, so the direct $0.33 is all it costs customers to plant the tree (the actual cost after credit card fees and the organization's operational costs...no markup for doing the right thing).

Does anyone know if there's a good alternative that doesn't waste more money into the system for doing something good? If I'm going to give up a percentage of sales to do the right thing, I want it to go 100% to that thing. We may just end up donating after-the-fact. But not as nice to show and for customers to see and take part in the process as it would be if we were able to integrated directly during checkout. But definitely not worth 45% less trees planted per dollar spent to do it, either. Definitely leaves a bad taste in the mouth.

I  just saw came across this on Sprout website when investigating adding to my website! Totally gross 😠 Especially because SS does not disclose this anywhere as far as I can tell and in fact don't even provide support for extensions because they are claiming to have nothing to do with the extensions beyond being connection between us and them. So they can't even say that the fee is paying for support costs! I wonder if they are charging all the extensions such ridiculously high fees?? So lame :(