Boosting Mcrit rate

So im rolling a Feoh as dualclass and i really like it so far :) But as far as i understand it, i need to reach ~320 mcrit rate to max out my critical hits so how do i do that in the cheapest possible way?



I have created a subclass adding 40 critical rate, and tried getting passive augment on my weapon (without success)



How much do i need to spend to get to get passive or active mcrit augment?

What else can i do to boost my critical rate?