ATLANTA — As in any economic downturn, the wave of home foreclosures has attracted voracious opportunists — investors among them who are buying, fixing and then renting the places out. In their wake are aspiring owner-occupants. How hard could it be, they ask, to pick up one of these houses on the cheap and make it livable? For an answer, consider Jennifer Kuzara, 32, a grants manager for a nonprofit organization here. From early 2009 to early this year, she spent about 1,000 hours on her foreclosure project.