I have now gone through a production upgrade of Magento from version 1.4.1 to 1.7. As expected, since I did a test run in my own environment, I encountered quite a few issues along the way, not merely limited to database upgrade issues which were a big enough of a problem themselves.
One of the issues I ran into that is now resolved was related to the individual product pages. When you selected a customized option for a product, such as a certain size, color, or other option, the price would change to zero. After researching the issue for a while, I came up with only other people having the same problem, but no solutions. Until this evening.
I came across this thread: http://www.magentocommerce.com/boards/viewthread/280283/P0/
I’ve also updated another thread in which I posted where someone else had the same problem: http://www.magentocommerce.com/boards/viewthread/284168/
The fix:
Replace
app/design/frontend/[YOURTEMPLATE]/catalog/products/view/options.phtml
with the same file located in:
app/design/frontend/base/default/template/catalog/product/view/options.phtml