Here is my fashionably late (or stylishly procrastinating) entry. Feel free to judge me.

Transfer Market

Starting Budget: 50 Million

Valdes-12 mill (62 mill)
Adriano-15 mill (75 mill)
JDS-3.5 mill (78.5 mill)
Pedro-15 mill (93.5)
Mascherano-26 mill (119.5)
Affelay-10 mill (129.5)
Keirrison-0.75 mill (130.25)
Bojan-0 mill (130.25)

Cuenca-0 mill (10.25 mill)
De Gea-25 mill (105.25 mill)
Ramos-40 mill (65.25 mill)
Inigo-15 mill (50.25 mill)
Neymar-40 mill (10.25 mill)

Formation + Tactics

Starting XI

For this lineup, the tactics won't be too different for our regular lineup. Alba will push forward more, while Montoya sits back. Busquets, Xavi and Iniesta will all play their usual roles. Our front line, however, should ideally have more freedom, with Messi occasionally moving out wide while Sanchez or Neymar go in the middle; movement and creative runs will be the name of the game. We want our offense to be at its creative best of where all three forwards can play anywhere in the front three, ideally like Eto-o, Henry and Messi, but hopefully even better. Keep our core tactics and strategies with domination of the ball, possession, and tiki-taka still being more important but play more risky passes and transition quicker on the counterattack.

Just to show our depth, I've subbed out all our players, but obviously we won't switch the entire eleven. Here, it's the right side that presses forward instead of the left and it's Alves providing the attacking. Thiago and Cesc aren't quite as good at controlling a game so Song will have to sit a bit deeper in order to protect our defense, make more of isosceles triangles with our other two mids as opposed to equilateral ones. Tello and Cuenca will stick to the touchline more, not drifting in the middle as much, trying to make runs in behind the defense for Cesc especially to provide throughballs. Ideally, Villa should not have to make those runs and should be more of a static forward in an effort to preserve him from injury.

Other Things To Note
-In addition to the players mentioned in the lineup, we will also keep Abidal and Puyol, and promote Roberto and Deulofeu. Abidal will rest/replace our center-backs in case of injury, and can also fill in at left back, while Puyol will be an extra sub at center back. Roberto is there to add extra midfield depth and Delo extra attacking depth, which will always be useful considering our players are made of glass. Also, I needed 25 players, so...
-Rotation will be the key to our success next season; our centerbacks must be rotated to provide playing time for our youth and rest for our older players, Xavi and Thiago will constantly be switching out, or playing alongside, Messi will not have to play the ridiculous amount of games he has been playing this past season, and in general we should be much healthier and more ready for those big games and not be plagued by injuries like we have been this season.
-By no means is a 4-3-3 our only formation; we have more than enough center backs to make three at the back work, we can go to five if we really want to; with the depth available in the squad the tactical versatility becomes a much bigger factor allowing us to address each opponent with a specifically tailored lineup suited to shutting them down. Whether this means playing a double pivot or five forwards or three centerbacks, we can and will do that in this system, thanks to the depth and rotation policies we will adapt.