Any simple shopping cart plugins for WordPress?

I’ve recently been looking for a simple to use, easy to install shopping cart for the Dot Design website.
This site is built on WordPress and it would be handy if I could find a plugin that could easy integrate into my current site design smoothly.
I’ve been considering Vendr.com because of it simplicity and that fact that other then adding a red button to the top of your website it doesn’t change anything hence no need for structure changes or fiddling about.
But its not free (though this isn’t a huge problem if its any good) and its independent of the site, meaning it can’t be styled.
So question is, are you currently using a shopping cart for your blog or WordPress site?
If so would you recommend it and why?