I think you misunderstood.
He meant that GNW Sakura will be in shop FIRST. THEN she will be a sign-in ninja.
Remember GNW Sai? He was priced at $40 - $50 or something in the shop. Later on, he was given away in a monthly sign in for free.
Pretty much everyone knew that GNW Sakura was going to be a sign-in . . just not immediately. . which is something that people shouldn't be surprised about. imo. She's a good ninja, so I also do not agree with people whining about be able to get for free when they want it immediately.