You should follow the budget procedure as outlined in
Local Unit Budget Instructions in the Help Center. If after the organizations have submitted what they feel they need there isn't enough total budget then it is the bishops responsibility to decide how to prioritize requests. Every unit is different and has different needs and I think more thought needs to occur than to just give an equal percentage to each auxiliary. But the needs of my unit really won't tell you what your unit needs. I've been clerk in two different units of quite different natures and the budgets have been significantly different for each.