i highy recommend nuri sahin, he performed admirably for me at arsenal ( also replacing fabregas, who is just **** ) he did cost me around 21M euros, but he managed to get around 30 assists in 45 games one season, averaging about 7.60 whole season . absolutely love watching him play.
Paulo Henrique, Javier Pastore (although they are advanced playmakers attack, Fabregas is better as support) and maybe Alan Patrick, but he needs to develop a bit.
ganso is his nickname he's very good btw, maybe even better than Kaka . but you might be wasting a bit his potential if you play him CM , he's more of an AMC (Advanced Playmaker) type of player.
You should not have to buy a replacement for Fabregas if you have looked after Ramsey and Wilshere properly from the start. They are two fantastic players and with lots of potential.
And yes, you should let Cesc go for £60m. That way you'll have enough to strengthen other areas.