I'm not sure what you mean by "setting." If you want her to do the work and buy some stuff she doesn't currently own, let her do the "setting" but offer or be prepared to reimburse her. I think it's still something to discuss in advance. She might buy an expensive hand made pure silk (not polyester) sari and set you back more that you expected.  
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Also, I think you have expectations beyond a certain costume appearance ... perhaps some out-of-costume activities?  
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That's why I think it's a good idea to find a good "appearance / performance" match FIRST and then see if she is interested in the costume add-on. Put another way, "Sure, I'll wear a costume but it's not coming off!" is probably NOT what you are looking for.