Found this site, seems (based on their figures) we had the biggest deficit in the 12/13 season of 11,5M and in the top 3 spenders!
Lots of 'Ifs' and 'Buts' and i know its not so straight forward but gives an idea.
Knowing the result of promotion seems like money well spent. The rest, as they say, is history.
http://www.transfermarkt.com/champio...ern=0&intern=1