I've had 4 contractors come to the house and give bids on tearing out my old, concrete driveway and putting in a new concrete driveway. All four of them gave extremely different prices ranging from $2500 to $5500. My driveway is 50 feet long and 10 feet wide. It will also need to be regraded to slope down and away from the house (right now it drains into the house!). Which is the fair price and which is the ridiculous price?