How do I apply for a provisional patent?

Tough question. You can try to find a patent agent that is working on their own. They often (but not always) are cheaper than patent attorneys. Generally i would say shop around and get a fixed quote. The bigger firms usually charge more than do the smaller firms or solo patent attorneys. BUT the only way you will know is to shop around. Also we are in a recession. Dont be afraid to set a budget and then ask if they can do the patent within your budget. Depending on the complexity it may be possible.