If you don't have a Realtor, you should get one to help structure the deal. You might be able to get $125k :)
Have you talked to your Realtor? Your Realtor or the Broker may know about programs in your area that buyers can apply for, from state, county or federal funds. Often there are federal HUD funds available that are administered through the county via a contractor. Check out: http://www.makinghomeaffordable.gov/get-started/housing-expe
Please keep in mind that while you may have an appraisal on your property, the buyers bank will do their own appraisal and it may come out lower than the one you have. If that happens, depending on how your contract is written, you may have to lower your price to the appraisal price or the sale will be cancelled because the buyers bank will not loan him more money than the home appraises for.