Related Cos. is talking to several prospective tenants to take Virgin Megastore’s Union Square space, according to the Post. Sources said the asking rent for the space has dropped to $15 million per year from $25 million. Some of the prospective tenants include CVS and Best Buy, which reportedly is looking at the Circuit City space on the same block as Virgin Megastore. Forever 21 might leave Vornado Realty Trust’s Whole Foods building a block away from Virgin and move into the space, but the retailer has seven years left on its lease. Virgin Megastore is closing in May or June.