There is no link to purchase VersaCheck 2007, because that version was discontinued and replaced with newer ones. I have checked the official website, and the 2007 version was nowhere to be found. Nowadays, only the X1 version is available for purchase.
You can verify this information using the following link: http://www.versacheck.com/web/creation.asp
Additionally, you should contact the developer of the application, because he might offer you additional options if you plan to buy an old product.