Locked in a price war with WalMart, Blockbuster Video has announced that it will slash the cost of a monthly subscription to its mail-order movie rental service by $2.50, and will increase its film inventory for the service. The new Blockbuster price undercuts WalMart by 55 cents. Meanwhile, the original online/mail order movie service, NetFlix, which had previously cut its monthly price by $4 to compete with Blockbuster, says the latest cut will drive customers away from Blockbuster’s own brick-and-mortar stores.