Hi,
I tutor online via the conferencing software and the phone or, if need be, Skype. I'm a PhD student in theoretical physics but in another life I would have been an English prof. I would charge you $90/hour to work with me on the verbal section of the exam.
$250/hr is too much. The suggestion of paying for improvements is not a bad one, but it's important to measure what a test company/tutor does for you by comparing it not to absolute change in your score but to how you would have done if you merely read books and worked problems. Test companies are all to eager to claim all student progress as a result of what they are doing for you.
You can read about me, and my strategy for attacking the GMAT, at:
NewEnglandGMAT.webs.com
Anthony