It may be "cheap", but there's often leins, tax claims, insurance, pain in the arse city ordaninces, assessments, and a 62 mills property tax rate there. That's not to mention crime. Grosse Pointe has a cheaper cost of living than Detroit.
Wait till they get their property tax, water, sewage, fire insurance, and any other cost the corrupt politicos can hit them with. As absentee landlords, the real shock will be their vandalism repair costs.