Maybe I am out of touch but this seems a little backwards to me...
Surely you should be approaching DPs that you feel have the appropriate approach for the script and director?
I am amazed anyone is contacting you with anything more than a speculative hello and reel link. Sending you a reduced price without knowing anything about the director or script seems crazy. It is not as if they can just send you their 'rate' (since it is micro budget)
Perhaps you and the director should watch some reels and reach out to who inspires you? Person 1st... Price 2nd?
Sorry to interject if my comment is not helpful.