Read more content behind paywall

I am looking for the following and allthough i think it is available somehwere, i dont know the keywords for finding the plugin.

When i write a post i would like to have it in 2 parts. First is freely visible to everyone who visits the post. But when they push the Read more button, they will be redirected to a Paypal payment option. After payment, the user will be redirected to make a login name. After that they can freely surf the whole domain.

I use s2member for the payment, but whatever i try with my posts, it is still giving the whole content to the free users. I used the insert more tag, but no success.

Hopefully someone can help me with it.