Somebody can correct me if I’m wrong, but I think Santorum suspended his campaign before incurring major debt.
Debt is a problem for the Bachmann and Gingrich campaigns, and at least so far, they haven’t been willing to accept a Romney buyout.
Capitalism is great for business, but buying votes isn’t good for government.
The two biggest reasons to suspend, I would think, are:
internal polls indicate a home state humiliation;
campaign is in debt and digging.
It’s possible Santorum’s campaign was flush before he flushed it down, but not probable.
(There’s a third reason but I have no grounds to speculate and I respect his supporters enough to refrain.)