I am the author of a similar source available package and selling to developers has been such a painful experience. They (we) have one of the most privileged situations when it comes to finances but they are so reticent in buying software. It's not that the software might not be good, or might not help them, but "it should just be free".
That has been my experience. Since my indie developer endeavour, I changed the way I see other solopreneurs and their businesses.
Let's support each other through projects like these and these types of licensing and stop taking things for granted.