The flash is now used--can you use it yourself? If not, and you sell it, you won't get $300 for it. Ask her for either the money or the prints that were promised. And tell the family! Maybe it will be the pressure she needs to make things right. Get her to take the pix off her site by doing as others suggested--contacting EVERYONE in the pix and letting them know what's going on and having them tell her to take them down as well. Make sure you have backed up her site first, though. Also contact the ISP.
If need be, take it to small claims court--it's relatively cheap. And start writing down all events that have transpired or will transpire until this is resolved. Write down times, what happened, and what was the outcome. Keep any voice messages (mails), emails, or letters, etc.
I am NOT a lwayer and am NOT offering legal advice, just letting you know what I'd do.