I'd be willing to chip in with manning, although obviously I won't be able to provide any beer, or indeed much knowledge or expertise beyond "Mmmm, beer foamy...." <!-- s:) --><img src="{SMILIES_PATH}/icon_smile.gif" alt="

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As for the legality of providing samples - I know at LRP events in England we operate a system whereby one buys "scrip" in advance (paper tokens in our case) and then exchanges said scrip for cans or shots at the event bar (which the organisers have bought in from the supermarket, or what have you) so it's not really doing it for profit. It may still be shady though, just that a blind eye is turned to it.
Alternatively, a few lads in one of the other Factions in the game system I'm in are home-brewers and they used to run a completely in-character bar, wherein you could buy (homemade) beer or wine for in-character money (small plastic coins that serve as currency in the game system, and which you "earn" in various ways)