Those prices were in the GM's guide in the last edition, so we won't probably have the official prices before RQG's GM's guide is printed. Or the prices may have been removed because RQG's adventurers aren't supposed to be roaming murderhobos who eat trail rations, but instead locals, who just happen to have adventures, and can just take the needed foor from their own pantry. You could perhaps make it a tax, so that the miltiamembers' households have to make the rations, or use RQ3's 1/10L per day.