Huge cheap ($300) leather bag?

If you feel comfortable buying from ebay, you can get a gently used Anna Corinna City Tote for a little bit under $300 if you're patient about it and don't mind a used bag. It's a great bag and certainly fits the HUGE requirement.
 
I agree that Hayden Harnett makes some great bags if you can get them on sale..I wouldn't pay full price for them, but there is currently a President's Day sale going on or you can check on eBay.