Just a note on the flak vest which people keep referring to as "m69" it's correct name is "armor, body, fragmentation, with 3/4 collar" or simply "3/4 collar flak vest". You'll get better search results that way, as there isn't a flak vest model named "m69", but I digress. Currently on ebay there are a bunch under $100.
Between the US 3/4 collar flak vest and Rogue One vest there are several notable differences on the zipper placement, shoulder stitching, collar stitching, and kidney area. One could probably modify it to get close as the zipper and side closures are all applied to the face of the vest and could be ripped off without causing any structural problems. Several nations made a very similar vest in the 1970s and 80s, so that might be worth keeping in mind if you're keen to hold out for the exact model of vest.