I don't have any experience with Volusion so I'll offer some other ideas. Like Bill, I wouldn't recommend any solution where the cart is being controlled by the other site. I looked briefly at the review Bill posted above and I see Volusion charges $29.95/month. Why?
You can get what I think would be comparable hosting for $10/month and there are many free shopping carts you can use. So why spend the extra $15/month for what is ultimately less control over your site.
One free cart that's been recommended to me a lot lately is
Magento. I haven't used it yet, but it does look like one good option.
I've been using WordPress for most content management solutions over the last couple of years. I think it's easy to work with as a developer and I think it's also easy for the site owner to use. It doesn't come with a shopping cart by default, but there are a few plugins available to extend the basic functionality of WordPress to include a cart. Some are free and some you'll have to pay for, but the pa ones are going to be a one time payment of under $100 most likely.
Other content management systems you can also look at are
Drupal and
Joomla. Between the two I typically hear better things about Drupal, but Joomla also has it's strong supporters. Both are full CMSs with shoping cart support either built in or through the addition of plugins like WordPress.
Two applications built specifically around shopping carts are
Zen Cart and
osComerce. As a developer I'm not crazy about working with either, but both seem to work well enough for shop owners. Between the two I'd sooner go with ZenCart.
Sites like Volusion offer the ease of use for a price. Their claim tends to be that in minutes you'll have a site up and running. My experience is that they aren't any easier to use than some of the applications you download and install on your own hosting other than the fact that you don't need to install anything or upgrade anything in the future.
However if you prefer not to install the applications and maintain them you can easily hire someone like me to do the work. Odds are that's going to cost less in the long run than the monthly fees you pay for the hosted cart solution.
None of what I'm saying should make you not use something like Volusion. I'm sure Volusion has many happy customers and I believe one member here (AaronHats) is using Volusion right now. You may want to ask him about his experience, since he's one here with actual experience. Just know that while hosted solutions like Volusion do offer a certain ease in set up they also lack a certain measure of control that you'll more than likely want or need somewhere down the road.