What's a simple, cheap treatment for my cluster headache?

Diet. Avoiding certain foods that trigger headaches, for example foods with nitrites such as hot dogs could help. Rest is also helpful and inexpensive.
High flow oxygen. 100% inhaled oxygen is effective for s moderate number of cluster headaches. It is challenging to use because you must have a tank of oxygen readily available - or remain near your source of oxygen. The other medications are typically more expensive. However, one of them, verapamil, may be less so. All of these medications need to be managed by a physician with expertise in cluster headaches.
High flow Oxygen. It turns out that 100% inhaled oxygen is reasonably effective for turning off cluster headaches for some patients. The problem is having a tank available. Many people keep the tank in their bedroom. Most insurance companies will gladly approve this therapy instead of more expensive of medications.
Simple treatment. Get adequate sleep and avoid stressful situation if possible.