Could also look at charoncart at charon.co.uk.
It's a good product and there is already a very well built
store ready for you to just customise and use. Cross selling,
feedback, recommend a friend, user's who bought this also bought
that and so on. It's a good product to learn from and relatively
easy to customise.
It's only asp and asp.net though, whereas webassists ecart is
both asp and php, and from what I understand limited coldfusion
although it might now be more compatible
Mat