That's because Chelsea don't put buy backs in. Hasn't worked out too well for them.I guess the only time when a youth player on loan would have a real chance to come back to City and play regularly if after his loan spell other teams fighting to sign him would be from the Barca, Real, Juve, Bayern, PSG level of clubs.
Price is a bit low imo no question Chelsea would have got somehow close to 20m for same player.