Firstly, I know my true market value, and have done for years - I always find a way to find out ;) and I haven't just got off the boat.
I also know what I can get away with making in this market, so what I'm making is not the issue per se, although this is below my normal rate, and I agreed to this on the grounds that were presented to me - which turned out to be completely false.
I work with many recruiters, not just this one. This one happened to have a job available at the time I was available...
Lastly, they point blank refused to negotiate, at all. Hence the need to fire them.