Falcao - no, We have RVP, I suppose you can argue that strictly speaking he would be an improvement playing as a backup to RVP, but I think we both know that he isn't really a practical buy.
Turan - not certainly, his goals and assists have not been spectacular.
Diego - Not sure which one you mean
Santi Carzola - 4 goals 4 assists in 20?
Toulalan - Web site I look at, him has him valued lower than Song.
Mexes - Is he better than Kos/Metersacker/Vermaelen?
Gokhan Inler - 1 goal and 2 assists in 27 games this season.
Erik Lamela - 19 year old
Bojan Krkic - 3 goals in 21 appearances this season.
Nice picks and a few probably on Arsenal's list to keep an eye on, but certain upgrades, no way. You might have me close on one or two (Falcao is a good Pick - Someone else said Alvarez), but you have to see my point about how hard it is to pick a clear cut solid buy at the moment? Even if you think Wenger should get them all, It is really difficult to find players.