You can choose zencart to setup a shopping to start selling products online. We have another thread in this forum in which some of our customers who are well known webmasters have added their review of different shopping carts.
You can see that thread from
Top 10 Shopping carts
I don't think that joomla has got any inbuilt shopping cart but you can integrate zencart with it. You will need to setup a paypal account and a $50 account with 2checkout to accept online credit card payments. 2checkout.com is very cheap and thats my favorite credit card processor. You have to go through this final hindrances as there's no other way to start selling good online. Selling in market yard with a stall would be too difficult and this initial pain wont be as difficult as offline selling.