Wow, that's ridiculously expensive! Especially considering the OFFICIAL client is free software.
I also think you exagerate with it not being a deal breaker. I don't know any software developer IRL that uses proprietary git clients, or other developer-specific tools which are proprietary.
Maybe most people don't care about FLOSS/propietary, but devs tend to care a lot more.
I'm in an office surrounded by people using Visual studio on windows, running Perforce. We do have some git infrastructure, and anyone that interacts with that uses sourcetree. I know that the diff tools of choice are Araxis Merge/P4Merge/Beyond Compare. There's also people using VisualAssist on top of Visual Studio.
There's plenty of developers who don't mind using proprietary tools
I also think you exagerate with it not being a deal breaker. I don't know any software developer IRL that uses proprietary git clients, or other developer-specific tools which are proprietary. Maybe most people don't care about FLOSS/propietary, but devs tend to care a lot more.