When I was there the U of H was giving Saturday tours of their observatory. Everyone met at the visitors center. I had rented a 4WD from Harpers and 3 other people asked to ride with me and offered to pay for the ride. 2 Englishmen and a M.D. intern (interesting conversation on the way up). Rental cost me close to nothing with their help. And, I talked all of them into hiking to the highpoint too!
So, go to the visitors center and ask for a ride from someone else who's there and offer $25 for the ride