There's a huge difference in players worth and market value. If say, Robinho had won you the Prem three years in a row and been your main outlet together with Zabaleta on the right, scoring almost every single decisive goal during that period... would you sell him for any less than 60M?
And on the other hand, if you had won the triple with Barca style play and Bellamy had scored some 30 tap-ins (with the odd beauty in the CL-final)... and now decided to leave on a free next season if he didn't get Robinho-money (with a unwritten rule that Robbie is the top earner), leaving you with a month to get things sorted or be royally effed... would you throw him into a deal that would land you Torres for 40M?
The deal is simply good business for both clubs. Though Ibra has been extremely important for us (most say better than Ronaldo, the non-fat one), the fact is that he wanted out and that we had become far too dependent on him which actually held us back in CL with a hugely static attack (mark Ibra = kill Inter's attack, force Inter's other players back to basics in remembering how the eff you played football other than hoofing it to the brill target man). It was a delight watching Inter destroy Milan 2-0 the other day (Milito 2 goals, Eto'o yet to join) cause the players actually took some responsibility and worked together as a team and Muntari even went in for seconds after hugging Milito (the way ibra behaved after going out in this years CL he probably would have flipped him the finger!). We are on the move again, back to where we were 2 years ago when we probably were the best team in the world on the pitch (winning with 3 and 4 goals). Everything is there; from a United/Liverpool-stopping midfield, to world class defence, to the best goalie in the world, to a couple of die hard attackers (and let's not forget Balotelli) who will get the job done without the whinge. All that's needed is someone who will feed the ball or for the already present players to start taking responsibility again. And with three class finishers on top... hey... there's quite a few targets to aim at...
And Barca... Well, let's hope he they don't get Ibradepende (an actual phrase) and that he doesn't get fed up and destroys the team moral. If they don't and he doesn't, they will have a player with unbelivable athletic abilities and skill, that for the first time in his career wont have the responsibility of carrying the team, in a new no marking enviroment. I mean, this could be absolutely devastating seeing how he usually taps in on the close attention of at least two defenders. And against teams like Chelsea which provided them with a lot of problems last year, phew, it could potentially be a entirely different story with a holding number nine who's able to find the angles and "no-effing-way"-passes & goals. I mean, do you stop the supply from the midfield or the one from Ibra? Meanwhile, who marks Henry and Messi? If they hadn't gone for him, risk and all, they would have been faced with an entirely different beast next year when Eto'o left. Who would they hire? How much would he cost? Would he accept a salary below Messi's? Who else would accept Etoo's salary demands except Inter if it came down to another transfer deal (Ibra was already on 12M euros so Etoo's salary... meh, why not? There's already some extra 40M in the piggy bank)? How many of the world forwards actually ticks the boxes Ibrahimovic does? Adebayor? Not even close, and he's like 30M... and City weren't even THAT desperate... (note; not saying Adebayor is shit, I just don't think he's anywhere near the standards of Tevez and RSC, or Ibrahimovic)
So, when looking at the deal you can't compare Ibra and Etoos qualities and what fancies you, instead you have to look at how they fit into their particular teams future at this given time. The deal was a bargain and oh eff did we come out on top, Eto'o and Ibra are shit but oh boy are they good...
The alternative of them staying would have been extremely bad for both clubs, but 40M more so for Barca than us. Our grumpy player would have walked home another Serie A title and still be worth something next season...
And that's why deal is what it is.