but now you know that you're NOT a favorite client of hers...sorry

If you see her again let her know before the session that you saw her ad and just want to "confirm" that the new rate is XXX.

If she balks...run...run very fast.

This is simply a business...conduct yourself accordingly.  Would you pay $ 1 a gallon more if the station across the street is selling it for the $ 1 a gallon less?

You don't owe her anything...except the donation in her ad/site.  And if she plans on jacking you up for more, and you go along with that, you better examine why you're here in the first place.