This plugin is REALLY buggy. I mean seriously seriously buggy, and as far as I was researching, the commercial version (golden cart) doesn’t solve these issues. I am working on a shop right now and I have installed a couple of versions of wp-e-commerce, each one has it’s own problems and I am sure it was designed to pull as much money from people as possible.
The best solution – don’t use it unless you have three months for solving all the errors.
It is such a shame though, WP is an amazing tool, personally haven’t had a single problem/bug.
If anybody knows a solution for variations in wp-e-commerce 3.8 and above please let know, there are (I think hounders) of users who are posting similar question.