Four years ago, real estate investment company D.R. Stephens & Co. stopped buying land in the Sacramento region, saying land prices were just too expensive to make a solid profit. But guess who has returned? The San Francisco company is putting together a $150 million fund that will focus on the Sacramento region, buying property that developers and homebuilders want to sell as the new-home construction market continues to struggle. Some analysts say they were waiting to see when deep-pocketed investors, like D.R. Stephens, would return to the local market, looking for bargains on what was once pricey property. D.R. Stephens will not name potential investment partners in the fund, but the company plans to raise the $150 million by this summer.