Regarding Mourinho, I've always been amazed by his work in Portugal.
At Leiria he barely had a cent to spend, and led them to 5th place their best ever league finish at the time in 2000/2001 (ahead of Benfica who he'd left earlier that season), and then to 3rd place midway through 2001/2002 (ahead of both Porto and Benfica I think), before leaving to take the Porto job.
I think that his time in charge at Porto coincided with the building of their new stadium (which I've been to many times - it has the best club museum I've ever seen bar none) ahead of Euro 2004, and so money was very tight. During his 2.5 years there, the transfer fees on player sales clearly exceeded those on player purchases (I avoiding using the word profit as a sizeable % of the transfer fees on player sales probably didn't go to the club). I think his most expensive signing was Benni McCarthy during the summer of 2003, as a replacement for Postiga who was sold for around double that amount to Tottenham (the text-book definition of a mid-table club at the time).
And as I've said many times, at the time of the 2003 UEFA Cup final, Martin O'Neill's Celtic team cost approximately twice as much money in transfer fees to assemble compared to his Porto team, and had a significantly higher wage bill. That's before we even get to the CL win the following season.