that fee seems steep to me, given how much you can learn here on SDN and through books available at libraries, amazon, etc. How much more can they offer?
I learned a huge amount calling and speaking to each school's admissions office for the schools that I was targeting, many things that I learned were not intuitive to me and felt an awful lot like jumping through hoops. If you could learn how to avoid all the mistakes I made, $500 doesn't seem a bad price to pay. But part of what made me competitive this year was the notes that I referenced in my apps -- 'I spoke with person XYZ from your office and am applying because of reasons ABC that we discussed'. Several schools specifically said that they looked favorably on applicants who showed specific interest in their school through conversations with admissions directors.
My concern would be how an admissions consultant could keep current on 129 or so medical colleges, considering from what I found, many colleges are seeking very different things in an applicant, and these things change over the years.