The type of data in which AVG will sell does not include detailed personal data such as credit card information typed, name, address, or even your email address but will sell a users complete browsing history and sometimes personal information can be stored into this browsing history depending on the web site.
In addition to browsing history, your IP may also be shared with AVG search providers and affiliated vendors may even have access to your email address.
The selling of personal information is only affecting the free AVG product which it offers to users completely free, or maybe not so free now? Users have the choice to utilize the free product, move on to another free AV product like Avast or accept the free product in exchange for some of there data being sold in exchange. What choice will you make?