WP eCommerce is fine, it’s free so you can’t go wrong. It does the trick and will take payments via PayPal. It’s a very complex plugin and not everyone is happy with it though. The developers website is http://getshopped.org – try it out and see what you think.
Be advised NOT to purchase any of the “premium” features (such as Gold Cart, Members Module, Affiliate Module etc). The developers support is dreadful and often things just don’t work. It’s a constant beta version IMO.
You’re much better off using WP eStore. I use it and it’s awesome! It’s much slimmer than the above and makes your website faster You can add products anywhere on my site, not just on the “shop page” – so if I’m talking about a product I’m selling then I can include a Buy Now button there and then. It’s not free but it’s a purchase you won’t regret.
There are several others like Jigoshop.com which I’ve never tried, but I know it exists and it’s free.
Search for “WordPress Shopping Cart” or “WordPress ecommerce” for other products.