Well it may well be illegal not to produce accounts, but it seems to me (and perhaps Litebulbs could correct me if wrong) there is nothing to stop BASSA paying their reps any sum they like without contravening any law (provided appropriate taxes are paid).
Whether those sums will be deemed fair and reasonable by the membership is another matter obviously.
However, many BASSA members are apparently happy to support their leadership in further strike action, thus foregoing significant sums. With this in mind, are they likely to get too upset by a possible misuse of a portion of their £15/month?