In the aftermath of the housing market crash, contract-for-deed sales in the metro area have soared more than 50 percent in the past five years, as families with low income or bad credit are lured by the promise of homeownership. The purchase price can be twice what the property is worth, records show. On average, contract-for-deed sales were about 10 percent above the estimated market value as set by county assessors. To get a handle on the growing business, Minneapolis officials recently began their own examination of contract sales. They believe many rental property owners are using contracts for deed as a way to avoid maintenance rules, shifting the cost of expensive repairs onto their buyers. Indeed, hundreds of contract sales in the Twin Cities involve former rental properties, many with a history of problems. Regulators in several cities said they are alarmed by the Star Tribune’s findings and frustrated by their inability to do more to protect buyers. Local officials are vowing to push state legislators this year to require greater disclosure from sellers.