Infomercial marketing firm National Media Corp., Philadelphia, this week finalized a $30 million agreement with an investor group led by Stephen C. Lehman. Lehman is chairman and CEO of Premiere Radio Networks Inc., a unit of Jacor Communications Corp. As part of the deal, which still requires shareholder and regulatory approval, he would become chairman and CEO of National Media. A shareholder meeting is expected this fall. About $20 million of the total sum would be invested directly in the company to finance operations, while the remainder would be applied toward acquiring shares of its series D preferred stock. National Media has posted losses for the last year and a half, but has received at least one favorable review from stock analysts. Investment firm Waldron & Co., Irvine, CA, indicated earlier this week that it had issued a "buy" rating on the firm and valued its stock at $8.75 a share. National Media did not return calls for comment, but Lehman issued a statement saying he was pleased that the company's senior managers offered to personally invest more than $5 million in the company.