whats worrying is the price hike when filming is involved
raising a few questions
does she advertise filming on her profile (and if yes is it included or an extra) if so then she can do what she wants its a free market
did you come up front about the filming with her from the start or did you wait till the last moment (its a bit of a low blow if you were not straight up about your intentions)
finally did she just make up prices after talking with you altering the deal however she sees fit (if thats the case thread with caution who knows what else gets altered)
side note do your research on the girl (is she known, is she a new face does she have histry) also if you are filming her and shes okay with it (potentially going on the net) i doubt she will e bothered you showing her profile (okay that with her some providers arent bothered some only allow it for personal use some want a copy for their own marketing)
fair price is what you are willing to pay (does she look good enough and will she provide the service you want and how much are you willing to cough up of it) shop around before you commit and have a plan b, and check your budget how much do you want to spend maximum then work from there
generic answers for generic questions
some girls allow filiming with no extra charge some will want it of a certain standard and charge extra it depends on the girl