Man United have spent just as ludicrously as City. De Gea, Ferdinand, Jones, Carrick, Young, Valencia, Rooney, Berbatov, Van Persie.. The period of time over which the spending occurred matters little to me - it would make sense for United's to be spread out, they've been doing it for longer. The biggest difference is, in my opinion, City used their money to bring exciting football to the PL, whereas United have decided to become the ultimate grind machine, whose tedious football needs more luck than ability or talent to yield success.
I don't agree with City and Chelsea's policy, as it has hampered my club Arsenal considerably, but at the end of the day it isn't their fault they were bought by a billionaire. And, as I said, at least City are using their money to make the league more exciting. One thing I don't believe, however, is that you need money to win things. It's entirely possible to put together a quality group of players capable of competing, but it's simply a matter of keeping them together.
Anyway, I'm bored of watching United win undeserved titles, so I hope City or Arsenal can win this one and a few more teams can compete strongly next season.