I personally recommend 1shoppingcart.com. I've been using it for my BizMotivation.com website for 5 years and have run more than 5,000 sales through it.
They offer a full-month, all the bells-and-whistles trial for only $3.95. It's a great way to test-drive it and see if it's what you need -- without further obligation. Also, they've got helpful, easy-to-follow videos that show you how to set everything up.