I would recommend that when she writes back tell her that you see that her rates have increased since you sent the inquiry and that although you really wanted to see her she is now outside your budget. She may bid you farewell or she may honor the old rate. I have had a situation where I forgot to update my rates on p-411. When a client mentioned it I honored the old rate for him and quickly updated my profile.  
Honesty is always the best policy. It is not offensive to inquire about the rate.

Yeah, I'd mention about the rate increase. Nothing wrong with asking questions. If it's not the answer that you are looking for & you are uncomfortable about the whole situation then you're better off finding another provider. Plenty of other beautiful providers out there that will provide more for your needs.

If you sent the booking request before she raised the rates (with all the required screening information and requesting a date, not just a random email for a future visit without specifics), she might actually take that in consideration and for this time, honor the old rates. it's totally up to her, but that's what I would do (and have done with everybody that booked with me or sent me full screening information with a specific date request before my last rate change).  
In this particular case I don't think it would be offensive to politely ask.  
Good luck and have fun!  
Delightfully Yours,  
Sofia