Being very lazy, I can never be bothered to travel an hour on the underground just to get to a punt.
You must ask yourself.. What can a punt do for you?
An hour's travel is reasonable. No stress driving or parking anywhere. Probably within walking distance of where you need to go. Fair pricing at £70 an hour..(supply and demand).
If you have a particular type, there are plenty of nice ones in your neck of the woods.
Someone mentioned the prices may drop even further due to economic times, london will be the first to do so if they do. On AW, feedback is king. Add that to your research and away to go.