Can someone tell me what's the best free wordpress shopping cart from their experience. thanks in advance.
Well, there aren't many. Good ones at least. I've tried most and the only one that worked was WP e-Commerce by Instinct. Problem is their support is garbage. So you are left to your own devices if something doesn't work. There are a bunch of smaller e-commerce plugins that dont have many options. How many products are you wanting to sell?
I've used WP-Ecommerce and it was fine. You can make it work how you intend with the right knowledge.