"Daily Mail offers gazillions for property website..."
Gazillions means 'a very large number' but then so does jillions, squillions and zillions. Make your own word up as long as it ends in 'illions'. On the other hand, millions, billions and trillions are definite amounts and pillion is the only word ending with 'illion' that has nothing to do with numbers, because it's the seat behind a motorcyclist and there's usually only one.
Being OVER A BARREL, in a difficult situation, comes from people being strapped over a barrel and flogged