Before I begin I ought to say: yes, I know that schools don't have much money, and that many leaders or heads of Computing have no budget to speak of. But it wasn't always that way and it won't always be that way in the future. Besides, some readers of this website do have money to spend and make decisions about.
If it's within your gift, I would say there are two things you should do with your budget. They are devolve it, at least partially, and set some aside for projects, in what I call an innovation fund.
Terry Freedman is an independent ed tech consultant and freelance writer based in London, England. He publishes the ICT & Computing in Education website.