Um, why would you be paying a tradie in beer rather than cash, unless it were to avoid tax? By law, they're supposed to declare the value of the beer as income, and remit GST, and pay super, etc. on it, so doesn't giving $50 of beer rather than $50 cash just overly complicate things?
Of course, that's not what happens: the only reason a tradie would ask for payment in beer is because they're intending
not to declare the income, pay GST, etc., in which case
you can't claim the expense, either.
Paying tradies in cash without a receipt, or in beer etc., is being complicit in tax fraud. I'm not suggesting it's crime of the century, but you have to know that you at least have to keep it on the down-low and not be claiming the beer on your tax return!
If you think you can claim the beer, then to quote from the Princess Bride: "I do not think 'legit and reasonable' thinks what you think it means".