If you have a decent sized tractor, a scraper is probably the most economical way to go. Check out the following link
http://www.sieversequipment.com/ and follow to the Leon and Reynolds websites. A decent sized scraper will cost you $15 - $25K and you'll need about a 200 horsepower tractor to pull it. Might be cheaper to hire someone to do it for around $70 - $80 per hour probably.