Maybe you need to lower your standards. Cardiff aren't exactly rich, so you are unlikely to be able to sign players that want high wages. You could try asking the board if they will allow you to increase the maximum wages you can offer a player, I have never played as Cardiff myself though, so I don't know if they are willing to do that. The only other things you can do are pay the agent a higher fee, or offer the player higher/more bonuses, that will usually allow you to lower wages a little.
I would probably just target younger players with good potential since their wage demands are usually much more reasonable and you can sell them for a profit later on if they don't work out for your team.