The board of directors of Essel Propack, which met today, approved a proposal to buy back shares at Rs 390 per share.According to a release issued by the company to the BSE today, the aggregate value of the buy-back shall not exceed Rs 57.50 crore.The stock closed with a gain of nearly 3% (Rs 11) at Rs 371 on the BSE today. The counter logged a huge volume of 1.10 lakh shares as against the two-week average daily volume of 28,000 shares.