Here's an interesting analysis of Scotlands financial position - it's 10 years old now but it still makes interesting reading:
http://www.scotland.gov.uk/library/documents-w 3/gers-09.htm
Basically if you take all of the revenues for North Sea oil and independant Scotland would have a Government borrowing requirement per head roughly on a par with the UK.
However -and I know this will be a shock to many regulars - but there's more to a consideration like this than just the finances. I think John implied this in the question.
if such a split happened without an ovrewhelming majority you'd have a large split in the popular mood and unearth all sorts of trouble.
Just seperating the systems of the two countries would be an organisational nightmare too. - Not that it couldn't be done, we underwent a messy divorce with Ireland 80 years ago
Not the sort of thing to be done lightly