At what point, and under which hat, are you willing to pay? If the Federal Reserve handles it lender of last resort duties, as it should have when Lehman Bros. went under we wouldn't be talking about this, AIG and others went into the sick ward because of this failure. Had Lehman been allowed to call on the Federal Reserve the immediate cost would have been in the $40B range, but they were allowed collapse instead of an orderly liquidation. That $40B then became $400B, meaning the Fed no longer had an asset sheet deep enough to cover it. It then went global and ballooned to $4T dead minimum worldwide.
The next hat to try is the US treasury. The congress could authorize several methods here, the best being make all the money the Fed needs to avert the crisis available. That was the $700B and deeply flawed package, and it might work.
Now, let's look at the next cap you could use to help the banks pay their creditors (you and me). If the banks fail then their insured creditors are going to the guy with the FDIC cap. This is the most expensive possible choice with the least possible return guaranteed.
If you still won't pay? Everything collapses in value, adjusted to the T1 money supply right now. T1 money is currency; there is currently about $827B of this, all else is leveraged off of this. I am dead serious, farmers won't be able to plant their crops, vendors won't be able to restock their shelves, gas stations won't be able to buy the next load of fuel for their tanks, power plants won't be able to buy their next delivery of fuel, and employers will not be able to pay employees. This isn't a might happen, it is a will happen in that event.
Re-capitalizing the banks will cost the US at least $2.5T before it is all done. The banks weren't being especially greedy. The banks bought loans in lots and accepted the risk with an agreement that the firms selling these would buy them back if they reached a certain failure rate. The problem is the people who took the loans then defaulted don't have the money, so their blown out. Then the companies that issued and sold the loans payed what they could and were blown out. The banks got stuck holding a bag in a lot of cases, and they did what they could before asking for help.
If the government had not acted to re-capitalize the banks, the price (interest rate) of available capital would go up until the potential return justified the risk. This still would have caused a very serious depression. The banks have paid dearly for their misjudgements, look around the world at how many have failed. I just want to keep the system alive because I know what happens if I don't. I rather like to eat.