There are other loan programs out there that may accept less. One of these is FHA. FHA's website states: "Minimum credit score requirements for FHA home loans depend on which FHA loan product the applicant needs. Generally speaking, to get maximum financing on typical new home purchases, applicants should have a credit score of 580 or better. Those with credit scores between 500 and 579 are, according the the FHA guidelines, 'limited to 90 percent LTV'." (Reference: http://www.fha.com/fha_article.cfm?id=200.)
You could look into rent to own, land contracts or sub2 agreements.