Manchester City. Budget : 82 Million.
Need a consistent MC. No older than 26 and value must increase
Can't tell how old they are if you don't say which season. I'll take it you're on season 1.
Fabregas - He's a good consistent MC but people have always had trouble with him performing at Man City but I think you should just try and give him chances. He's going to cost around 50 million probably but he's good when he gels with the team.
Aaron Ramsey - Young and not as good as Fabregas and probably will never be equal with him but he is much more consistent and does the job even better most of the time, well in my experience he got better avg. ratings. Much cheaper, if you're lucky you can pick him up for around 8 million and his value can go to 13 million usually if he picks up the young player award which he should do since he's around 18.
Marouane Fellaini - Plays for Everton and might cost about 25 million to buy but he has very good mental stats which make up for his lack of technical skill. He's 24 and he might not have a raise in value.
Sergio Canales - The one and only, you probably know him already but he starts as an 18 year old and on the 10.3 patch he is already set to join Real Madrid and it could cost maybe 60 million to take him from them after he joins or he could be dead cheap, up to 10 million if you're not on the 10.3 patch. He is one of the best players to increase their stats and becomes a world class playmaker who would be worth alot. Maybe even 30 or 40 million if you get him cheap.
Toni Kroos - Similar to Canales but starts on loan and you can get up for around 12 million on the first season before the 10.3 patch which I did and he was worth every single penny. Otherwise you could be spending alot. But his value will go up quick as well.
And that's all of the best midfielders who met your requirements, I could think of on the spot without having to open FM up.