200 LEDs is quite a bit to run on battery power. I use one of these 12v batteries .. http://www.sears.com/shc/s/p_10153_12605_00911221000P?sid=comm_sears_other
... and four 5v 12V car adapters 1.2 amps each and it only runs 70 LEDs for an hour.
Providing more details on what your end goal is would help. You say you want this to put on two helmet visors and needs to be see through. I would suggest you test the minimum size / separation to see through with a few LEDs and compute the maximum LED count from that.
I hope the battery details help.