To be honest I haven't found unresting a player makes it any easier to sign them this year. In previous FMs you could make them unhappy, the club would transfer list them and you could pick them up for a reduced price and that was very unrealistic.
I haven't been able to get a player transfer listed this year, even after the player missed training regularly, nor have i found that you can get them cheaper when they are unhappy so I have pretty much given up unresting players.
I have made all the good Arsenal players unhappy though, and they all played badly that season and nearly got Wenger sacked!