The newly-promoted Black Cats were among the Barclays Premier League's biggest spenders during the close-season as Keane added 12 new faces to his squad.
Keane has steadfastly defended his recruitment policy against charges that he had paid over the odds for some of his new arrivals, many of whom arrived on Wearside with something to prove at the highest level.
Quinn said: "We back our manager - we believe in him and we are prepared to fund that belief.
"The big mistake that happens in football is where signings are made for headlines and season tickets and then football is in there somewhere.
"At this club, football comes first in everything.
"If Roy Keane fancies a lesser-known player in favour of a ritzy-glitzy player, then that is the player I will go for every time.
"The higher you go, the more difficult things are to achieve. That's because we haven't been hanging around the top of the Premier League attracting players for the last few years.
"We are playing catch-up again in a way, but we think that the idea of Roy Keane coming up and developing a career in front of 48,000 fans every week is a big thing.
"Players in general get stick for always just going where the money is. But I think sometimes we do them a disservice.
"There are some great players out there who know what the best football clubs are about, and we wanted players coming here who wanted to wear this particular jersey with pride.
"Roy stands for something and people in football know that, especially after last season."