Hi Michael,
Lots, these days, but it will usually be an option on anything that’s not a premium-badge car. The most affordable models with powered tailgates will be the likes of the SEAT Ateca, Peugeot 3008and Ford Kuga. It’ll be an option on the basic models of those cars, but usually not too expensive an option. Some compact estates, such as the Volkswagen Golf Estate, can also be fitted with an electric tailgate, so check the spec sheet of any car in which you’re interested to be certain.