On his Internet Business Journal blog, Mark Quarles outlines a "hole" in 1ShoppingCart that can allow technically savvy visitors to your website to purchase your products for much less that what you have intended.  Mark provides the full details in this post, however the gist of the problem is by not deleting old testing URLs once shopping cart testing has completed.  This problem can also apply to Clickbank Item ID URLs as well.

Marc Quarles will be offering a product creation workshop for a limited number of his blog readers. The workshop will cover the full product creation lifecycle from market research through to arranging JVs and marketing. Dates and any costs for the workshop are have not yet been released. View Quarles' blog for more information.