Alternative funding for alternative education can be sourced from a number of places and in a number of ways. A simple sponsorship deal can only be done if its allowed in the area that you live in. You have to balance the deal with any effect it will have on the school, whether it's through the business of the sponsor or the reputation of it. For example, a fast food company sponsoring a school will bring in money but will encourage people to eat fast food. In the UK for example a chocolate bar came with vouchers for gym equipment, the irony was noticed by all.
You have to be careful that the sponsor doesn't have any influence over the school and its running unless its beneficial for all. Don't alter history to reflect the sponsor, for example, don't alter the teachings for how man developed on earth because you have a science sponsor or a religious sponsor for example. Sponsoring isn't the only way to go but can be a good one if done correctly and is researched carefully.
There are a number of places that alternative sources for funding for alternative teaching can be found. Many places offer subsidies to schools in order to for example build up a school garden for example. They may help with equipment and sponsor items to add to the care of the garden and this will allow money to be reallocated within the schools budget. Similarly if you get a building company into the school you may be able to ask nicely if they could accidental leave a few items behind.
Another way forward is to use donated equipment in the way its asked to by certain firms. For example a software firm may ask for help in testing a program and its development. This could be a case for the company to help the school financially with further software. Similarly if the school gets heavily involved in the testing they may even be eligible for a cut of the sales on the product.
Another source of income for schools is too produce items that can be sold to school families and to the locals as well. A school fair for example can sell donated good for profit for example. Also schools can make items to be sold during the fairs that can be made during lessons. These depend on the school and its abilities to decide what the items are. A simple piece of jewelry or a bakery item is an example of what can be produced and sold. This can also help the school if they teach children about running a business and how to make a profit.