I actually started with Foundry myself but found it (and the other frameworks) overkill in both size and the amount of stacks they offered. Especially as I was still needing to turn to so many third-party stacks to build the sites I wanted to build. So I built Source and can now do (virtually) everything I need to do with only it and the addon stacks. A lot of other people are finding the same thing - whether that is using Source for their own projects or for their clients as professional developers.
I realise that everyone has different needs and preferred workflows though. Different frameworks simply suit some people better. There are big fans here of all the available frameworks.
I wrote a blog post a while back that might help.
But yes - long story short - Source is free to start so there is no harm in giving it a shot 