Well, they did say this was for the "forward bases" (read, bases located inside enemy controlled or sympathetic areas). Keep in mind that they also said that for every 24 convoys, they lost on average 1 person. There were probably at least 1 injured for each killed (maybe many injured for each killed). Ignoring any death benefits, how much do you think it costs to keep a marine in a hospital (after airlifting them back to the states or elsewhere in the western world) for a few months and pay for lifetime visits to the VA? 399 to 1 sounds conservative.