a) Ignore her communications - she'll eventually get the hint and take you off of her "email / text list"

or  

b) Be honest and say "loved my time with you but I can't personally justify your rate" and see if she liked you enough to throw you a lower rate bone.  Some girls get miffed at this, some girls are willing to work with clients who treated them nicely or who they enjoyed more than others.  
Maybe she'll keep you in mind when she has a cancellation or two during her tour and will randomly send you a lower rate to stay on track in terms of her financial goals for the trip.  In fact, maybe say that: "Please keep me in mind if you have a cancellation or offer promotions at any point during your trip".

Just being nice and not being dick-ish goes a very long way with an independent.  
Way longer than many realize.

-- Modified on 5/18/2013 8:49:44 AM

If the emails and texts are addressed to you personally I wouldn't ignore them. Especially since you met her. I would respond by thanking her for thinking of you. That you enjoyed seeing her last time; but unfortunately you will not be able to see her this time; you don't need to give a specific reason. If she persists you could mention she was a special "treat" for you to see rather than saying too expensive

You are a repeat.  She might give you a return discount, esp if she had fun.