I doubt that very much. There is a point of diminishing returns, I agree. If the charge were $1, less people would leave than if the charge was $100. But, the value of facebook or other social networking sites is in the social aspect.

For pay services have competed favourably with free services. Ringtones are one example where people opined that paid services would fail because free options would emerge. And yet, people still pay and download ringtones.

The catch to making people pay the $1 or $5 is to make it easy. If you require them to pull up a credit card or some such, you will lose people. If there was a simple way to pay such that the money came out of some account (PayPal or some such) then you'll get the $1 in a heartbeat.