Can I leave my friend's gig before her set when the running order changes?

At 9:35, my friend came out from backstage and said her band's set had moved to 11:15. I said my last bus left at 10:50. She looked at the room and said, 'There are only twelve people here. I really need you to stay.'

She'd invited me to her first gig with this band, telling me they expected to start around nine. I paid the $12 entry fee, arrived before eight and helped carry a keyboard case inside. I also told her I needed to leave by 10:35 to reach my bus.

A taxi home would cost about $38. I could pay it, but that would more than triple what I'd planned to spend, and I have a 7:00 shift the next morning. She suggested I skip a different night out next week. That irritated me more than the delay, though she looked nervous rather than demanding.

I want to be there when she walks onstage. I also don't want every change to the gig's timetable to become mine to absorb. What can I reasonably offer if I leave before the performance I came to support?

The timetable and costs are illustrative.