Wizkids Rules!

Wally West: Faster than Superman reads:

If Wally West is the first die you purchase this game, he costs 1 less to purchase.
Fast (Characters with Fast deal combat damage before characters without Fast.)

As long as Wally West is the first purchase I make this game, can I buy as many as I like for 1 less?
Does the ability persist until the end of turn? Or do I only get the discount on the first die of his I purchase, as long as it's the first die I purchase this game?

This purchase cost reduction applies only to the first Wally West die purchased.