last i checked greyhound offers 10% off your first bus ride when you signup for their road rewards program. If you have a student advnatage card you can get 20% off walk up tickets. Check their efares on their site.
Where do you want to travel? You may be better off with Megabus. Based on your profile information I am guessing you'll be traveling from Lansing, MI. You can take greyhond to Ann Arbor and then megabus.