Aseprite uses the sell the binaries model. It's open source but you have to compile it yourself (and it has many dependencies). I've tried getting things to compile before and I consider it about as appealing as a visit to the dentist (only longer and more painful!) so I just forked over the cash.
As stated by another user it's not true open source, the source is solely available for personal use and for the submission of patches back to the author.
Such a model can backfire though as it would appear to be legal for a third-party contributor to create a set of scripts that would compile and prepare the application (load all the dependencies in a container and so forth) and release those scripts. Those scripts could even become accepted by a Linux distro's package manager, similar to how package managers package freeware prop software by using a script to legally grab the binary from the developer's site and installing it.
Interesting. A sort of "sell convenience" model. I'm a bit out of this loop, but isn't this how several SaaS/PaaS operators work? Provide open-source software but offer paid-for solutions such as hosting and/or support?
