I've only seen this referenced once on here (in the transfers thread) but the KPMG EV report (linked below from earlier in the year) will be fascinating reading come next January. It quite clearly sets out the case that from a revenue to outgoings perspective we're far ahead of any other major team in Europe.
www.footballbenchmark.com
Long story short, it depends a little on how Levy perceives our finances vis-a-vis the stadium debt, but we've certainly got some headroom should some investment be made.