Volusion is actually a pretty popular paid cart. I have a friend using it for his business and they love it. One issue he had is that they host it and their bandwidth fees are very high. I set up a small virtual account for him and he runs a sub-domain through us to host all of his product images for their products and some national promos they have run. If you end up using them and have large product images with decent traffic you should look in to doing something like this to save yourself a chunk of money as their overage rates are $5-$7 per GB... yes, per GB. Their platinum plan is $179 per month and only includes 25 GB's of transfer, so know your traffic well before you start using them. If you hover around 1 MBPS per month and burn 200 GB's you would pay an extra $1225 to them using their bandwidth or you can get a virtual plan somewhere else and pay $9.95 running your images off a sub-domain.
http://support.volusion.com/article/...t-and-overages