I have used a few online store and market builders in the past and all have been ridiculously expensive, one even charged around £700 for 6 months so finding ZPeCommerce was a blessing.
Their price is brilliant and the customer service is excellent, they always respond promptly. The store its self has tonnes of features and is easy to use. I especially like the many built in payment gateways. I don't know how they can offer so many features, including SSL and domain for so little but its great. I would highly recommend!