The protocol for buying stuff is simple. First find good reasons why SIPB should purchace the item. Then convince SIPB members at a meeting that it's worthwhile. A vote will then be taken at the SIPB. If SIPB and IS approve of the purchase, then it can be made using an MIT requisition form.
Small purchases, such as money for making copies of an Inessential document, require only a SIPB vote.
If a purchase is made without prior approval, that purchase will be considered a personal purchase by the individual.