I bought qcad a few years ago (used it for a hobby project), I payed for it because compiling from source would have been a hassle. Note. qcad is open source.

I bought qcad a few years ago (used it for a hobby project), I payed for it because compiling from source would have been a hassle. Note. qcad is open source. But yes, there is a limit for what you can charge and how far you can scale that model :)