How do stipends work? Can pay be negotiated?

Absolutely sell yourself. I worked for a travel agency and after a couple of years I realized I had not gotten a raise. I then talked with my recruiter and advised her about this. She said she would get back with me and I got a couple of dollars more an hour. Even at my regular job I would negotiate my salary. They did have a scale from low to high pay so I know it’s negotiable.

Everything is negotiable.

Definitely, it can be negotiable specially if you are traveling out of state and depending also on the standard of living of a state you are going.