United sold him because he wasn't good enough. That might not be true any more, but he is not "proven" at the highest level in the Premier League. He was always devastating against the bulk of the league, but against the big teams? Not so much.
I think City probably looked at what they were lacking in that Champions League final and a player who can reliably dribble and carry the ball into the area was one, and a real top class #9 was the other. In terms of the money I don't think they care too much beyond the implications of FFP...
I think he's doing the right thing. The club convinced him to stay by promising him investment and the ability to leave if that investment wasn't forthcoming. If they can't honour that then he shouldn't feel any obligation to them beyond what he cannot legally avoid. I think Spurs would be wise...
I can see people wanting to create a narrative about oil money, and for sure it's a massive factor, but let's be honest, Barcelona are in the position they're in because of gross mismanagement first and foremost.
I don't think the price tag is much of an issue for anyone at City. The only obstacle that has ever stood in the way of their spending is FFP. I think this deal will happen and I think the Kane deal will happen too.
Mate he's pretty much said to the world that he wants to leave. It's been reported that he was celebrating Spurs letting him leave at his bothers wedding or something. Most of the ITK's think his move to City is a done deal.