I have bought from Michigan Synth Works. I would buy from them again.
I find Mutable Instruments stuff to be powerful. But you really have to learn and memorize the functionality of all the different modes to get the most out of them. They are surprisingly complicated when you consider that one knob might control three or four different parameters depending on which mode(s) you are selecting.
This tends to kill my modular buzz. I would definitely consider Mutable's stuff to be the West-Coast side of modular. How a module functions tends to be the most important thing to me after a few years of doing this... even more so than its actual functionality.