Partners In Profit can set up an online store for you to sell memberships and other items.
This demo uses the ECWID shopping cart service. Up to 10 items can be sold using this software for free.
Currently selling between 11 & 1000 items costs $15 per month. Other plans are available.
Paypal charges a transaction fee for securely processing the sale through the banks or using credit cards.
There are other online shopping carts and transaction processing options available depending on your needs & budget