User blog comment:B214/Talk About What You Want! 3/@comment-25290120-20141125182448/@comment-1359322-20141126105946

Actually Saji is a steal. Sona reincarnate Saji with 4 Pawn Pieces but she got more than she gained because Saji got the remaining Vritra gear and Sona has 3 Pawn Pieces left. If Saji had the Vritra Gear from the start, he probably would need 6 Pawn Pieces to be reincarnated, that would leave Sona only 1 Pawn piece left so Sona did get a steal on this scenario.

Gasper and Issei isn't a steal, Rias had to use a Mutation Piece on Gasper, but since Gasper is a goldmine like Otaku said it's fine. Issei unfortunately is the furthers thing from a steal. Rias had to use 8 Pawn Pieces on him even when he was weak. So Rias is actually paying at a normal price unlike Sona.