We make around 150k with our open source project too and there is no commercial license. Our revenue is from cloud and developer support. Maybe we should write a blog around that (https://erpnext.com)
Yes, that's the downside of making money with fully open source software - you have to find other means (support, hosting, ads...). But as an engineer - I really prefer to make money from selling the software itself - the thing I've created.
Please do; as noted above, lots of us would be interested in hearing the various stories of how groups have monetized open source successfully (and even unsuccessfully).
Sure will write it up sometime. We could do with some HN love :)