I think there should definitely be a 'Money' type subforum covering:
Finance (mortgages, student loans, credit agreements, bills, bank accounts etc)
Housing (threads about buying houses, renting, pics of projects etc)
Jobs (CV help, interviews, potential career moves, salary reviews, bla bla)
Economy
Gambling/matched betting
etc
I know I would probably spend a fair bit of time there, a lot of these threads tend to get buried in GD or end up with spam posts, a dedicated subforum would probably mean a better quality of answer, as it would be frequented by people interested in the subjects. Keeping the subject matter fairly broad (as above) should ensure it doesn't fragment things too much, at some point or other most people will want to ask/answer something to do with money in one shape or another.
On the flipside you would get less 'throughput' of casual readers posting in threads that they would otherwise never have seen, but that hasn't prevented subforums being setup (and being successful) in the past, for example the Football Stadium split from Sports Arena, splitting PC Games from Console Games etc.
Obviously, there are forums elsewhere dedicated to this sort of stuff (Martin Lewis enterprise), but that has never stopped OcUK from having subforums on specific things before.
In my opinion, a Money subforum is just a valid request (if not more so) than La Cuisine and On The Water.