OMG... Buying a backup player?
How crazy are you spending money to a player you consider second best.
Just promote a player from youth.
When you want to sign a player, than sign a player who is a lot better than one of your first team players. You manage a club to make it better, not to keep it on same level.
Don't buy second rated players, instead: Promote youth players and invest money for upgrading facilities, to even get better youth players in the future.