Try to sign nejc pecnik, he'll cost you about 70k and turns into a great player.
Stancu and Raul Rusescu both cost about 100k at the start as well and turn out to be great signings.
If i were you i would try to get Denilson from Arsenal on loan and maybe Jonathan Evans from Man U if you haven't updated your game.
If you signed these players you would have a couple of great youngsters who could turn into world-beaters after a few seasons and would also have about £3.5m to sign other players.
Can't believe i just gave someone advice on how to make rangers a better team lol :P | 
