Rising home prices and short supply have investors setting their sights on a new real estate play. Home flipping, loosely defined as buying and selling the same home within six months, fell out of favor during the housing recession, as falling prices left no prospect for profit. Now the market is on the rise again, and flippers are testing the waters, but the game has changed. This time, high rollers are taking the lead, backed by private-equity cash. The million-dollar flip is a high-risk, high-reward play, with investors catering to the latest architectural whims of the highest-end buyers.