“Actors who are asking me to add some tracking code are mostly interested in reselling users’ data,” Anashkin said. “Actors who want to purchase it outright will stuff it with malware depending on their level of greed: hijacking affiliate links, tampering with search results, showing popups with shady websites, etc.”
Anashkin’s experience appears to be fairly common. Developers have discussed these solicitations in online forums and several have written blog posts about selling extensions or partnership offers.
Getting them from Google is probably more expensive than trying to get a extension dev who needs money to do it.