I would have thought 500k would double his wage
No, he signed for Real Madrid on or just over £250,000 a week anyway and he did have clauses in his contract for a lot more.
For those mentioning "Why return to Manchester", you need to remember that place was his home from the period of time he turned from a boy to a man and he has a lot of friends there. He's stated many times that he misses Manchester the place.
In his heart I'm sure he'd rather return to Manchester United but financially Manchester City are in a much stronger position. But you also need to take into consideration the tax laws in the UK as well.
It's a shame he's in the situation he is in Spain (in ways other than the financial sense, which is far from a 'shame'), he broke the all-time scoring record in the Spanish League despite missing around 2 months with an injury and still it's a given that Messi gets World Player. He's the fastest player to ever score 100 goals in the Spanish League, yet Messi remains the games darling.
Let us not forget that Messi plays upfront on his own for the most part for Barcelona with Busquets, Xavi, Iniesta in midfield supporting him and the likes of Dani Alves putting in balls for him. Ronaldo plays in a team with a front line of Higuain or Benzema (and in recent times, both at the same time) and Kaka also joins in with his fair share.
Both Messi and Ronaldo have scored an equal amount of times (35) yet Messi's contribution accounts for 43% of Barcelona's goals and Ronaldo only 37% as well as the fact that Real Madrid have also scored an additional 13 goals this season. Not bad for a player who is being played in a more withdrawn role from goal over the last couple of months. Both are exceptional players, but it's frustrating when all you hear are people like Jim Beglin and Gerry Armstrong bang on about Messi whilst giving backhanded digs at Ronaldo.