As someone who has released a and actually wants to do more (and I’ve purchased assets to this effect on other development marketplaces) I’d only really ever touch a without full source-code if I was desperate for that feature. Even then, I’d be wary unless the developer was clearly active in development.
My take is that it only has value if its future-proofed with sourcecode and the added value is that you can update functionality or extend it if you have source too.