Why don't you pay every player in 48 months?
I could afford my whole team in probably 2 seasons.
First year I played a 4-4-2 with:
GK: De Gea
DR: Srna (18 - 48 month)
DC: Vidic
DC: Ferdinand
DL: Evra
MC: Marek Hamsik (48 months... dont know the price)
MC: M'villa (48 months... don't know the price)
AMR: Gotze (70 million - 48 months... but I wouldn't recommend him...)
AML: Neymar (55 or 66, can't remeber - 48 months)
ST: Cavani as a Targetman
FC: Rooney - complete forward.
Won everything.
Second year: started using Phil Jones in Ferdinand's place, bought André Ayew and Jordan Ayew because of their phisycal and mental stats and because they can play in various positions, bought Mbiwa because Smalling is good but not a good replacemente for Vidic, bought Aly Cissokho and a few bench players. Lost everything

P)
Third year: changed to 4-1-2-3
De Gea, Srna, Mbiwa, Jones, Cissokho, Obi Mikel (was tranfes listed), M'villa, Hamsik, Rooney, Cavani and neymar. Won champion league and Premier. The same as the 4th year.
In my fifth year I bought Bale for 50 millions (48 months, again) and signed Messi...for free! XD