I might be wrong but Ferguson (and Brian Clough) before him, always ensured he was the highest earning person in terms of the playing staff. £42,000 a day. Tax on that is just over £140,000 a week so, if it's just a normal wage/tax situation, poor Wayne will only take home £160,000 a week.
Add to that all the endorsement deals plus bonuses, appearance money and the usual free stuff that celebrity status brings, he's revoltingly rich.
I'd very much doubt that Moyes even had a say - Premier League managers don't sign players these days. The days of Brian Clough popping in for a cup of tea to sign you up are long gone.