It wasn’t easy for ASUS (2357) to hit that $199 price point with the Google Nexus 7 tablet, but it looks like it’s paying off. Reports of strong demand for Google’s (GOOG) debut tablet were reaffirmed shortly after the Nexus 7 launched, as Google quickly sold out of its entry-level model. Now, new estimates from based on touch panel shipments suggest Google could sell as many as 8 million tablets by the end of the year, making the Nexus 7 one of the most popular Android tablets to date. Google previously stated that it hoped to sell 3 million Nexus 7 tablets in 2012.